Change the fuel filter lately?

 

I haven’t actually, I’m not certain when it was last replaced…

I’ll try that too, something easily done at home with some mechanical know how?

 

Pretty easy. Clamp holding it to frame and a couple wrenches on each end to loosen it. If you can do a tune up you can change a filter.

 

I’ll give it a shot after work, anything against a Duralast filter? Local parts store doesn’t have AC Delco or K&N in stock.

 

Another possibility is a bad ERG valve.

 

Would I be able to just unplug it? It has a screened gasket on it and it’s been cleaned. I’ve had an EGR issue in the past with different symptoms.

 

@legginswill has the o2 sensor ever been replaced? As they get old, they get lazy, most noticeable at lean burn times, like light load highway travel.

 

Also, in regard to rusty bolts/nuts/fittings - what saves my day: after brushing it off, soaking with penetrating oil (Kroil in my case), before using a tool to loosen, I get at it with a punch and ball peen hammer and try to shock the hardware I'm going to loosen. I get as square as I can to a flat spot, and use a heavy ball peen, get some solid square tunks on the fitting. Some situations won't make sense, and common sense needs to be in control of the hammer.

Rust is a crystalline structure, and as it forms, it goes into an expanded state, and takes space, 14X original, which creates the pressure against anything moving freely. Impact can fracture that crystalline structure, collapsing it and opening the door for the tool to work without ruining something. Applied heat does the same thing, which is why heating with a torch works, but of course you wouldn't be doing that with your fuel line.

Works real well when a Phillips head is rusted frozen, get into the head with the correct Phillips tool and tap it hard a few times, axially in line with the screw.

 

@legginswill has the o2 sensor ever been replaced? As they get old, they get lazy, most noticeable at lean burn times, like light load highway

@legginswill has the o2 sensor ever been replaced? As they get old, they get lazy, most noticeable at lean burn times, like light load highway travel.

I haven’t replaced them, I figured a code would throw if the O2 sensor was leaning the air:fuel. Cheap enough and easy enough to change though, good maintenance anyway.

 

...or...or....if it ain't broke, leave it alone. Don't go looking for new problems...you already have one.

If you hook up a live scanner and can confirm a lazy sensor then maybe change it, maybe. But as you noted, no codes, so no problem...the truck will let you know (generally speaking) what it needs.

Changing random parts in the middle of a diagnosis -- not a good practice. Things like a fuel filter is an exception to this rule....new fuel filter always mo better (unless you do it at 8pm in the middle of winter and twist off a line...but I digress).

 

ALDL Scanner TBI / ALDL Engines Found | S-10 Forum

 

Let me ask this, because it’s strange…

As I drive it, it seems to go away. When I left work it was doing it, but as I kept going it eventually stopped and drove just fine. Kind of the same thing this morning.

It’s been rainy this morning, any chance the humidity is doing something? I’ve heard stories about this lady who claimed her Civic ran bad around 60% humidity or more, and it ended up messing with sensors. Any validity in something like that?

 

One example of that would be moisture getting into the distributor cap from hairline crack and causing ignition issues...so yes, weather related intermittents can happen.

 

A “cruise-speed stutter” in that 50–60 mph range on a 4L60E/4.3 combo is a classic gremlin, and the trick is figuring out if it’s engine misfire, fuel/ignition dropout, or torque converter clutch (TCC) shudder/slip.

Here’s how I’d break it down:


---

🔎 Common Culprits for Your Symptoms

1. Torque Converter Clutch (TCC) Shudder

The 4L60E locks the torque converter around 45–55 mph under light throttle.

If the TCC solenoid is failing, fluid is dirty, or the converter itself is worn, you’ll feel a “buck/stutter” as it tries to engage/disengage rapidly.

Usually no code is set.

Test: Lightly tap the brake pedal while cruising at the speed it acts up. If the stutter instantly goes away when the converter unlocks, it’s transmission/TCC related.



2. Secondary Ignition Weakness

Even with a “recent tune-up,” weak plugs, wires, cap/rotor, or a coil that only acts up under load can cause this.

At cruise, the engine is in lean burn — any weakness in spark shows up here first.

Test: Spray bottle mist test at night over plug wires/cap, or hook up a scope if you’ve got access.



3. Fuel Delivery

Even with a fresh spider, the pump or filter may be borderline. The CPI/Vortec injection is touchy about pressure (55+ PSI required to start, ~60 PSI preferred).

At steady highway speeds, if the pump can’t keep up with injector demand, you’ll feel a drop-out.

Test: Tape a fuel pressure gauge to the windshield and watch it while cruising.



4. Sensor Dropouts (less likely but possible)

TPS or ignition module intermittently cutting signal could mimic this.

But usually you’d get a code or more erratic drivability.





---

🛠 What I’d Do in Order

1. Brake-tap test at cruise → rules in/out TCC shudder instantly.


2. Fuel pressure check at idle, rev, and under load/cruise.


3. Double-check ignition (swap coil, inspect cap/rotor, wires — cheap insurance).


4. If trans issue confirmed: consider new TCC solenoid or valve body cleaning; worst case is converter wear.




---

My Gut

Given your description (“no codes, fine accel, fine idle, happens mostly at steady cruise”), I’d bet torque converter clutch shudder is the leading suspect. The brake-tap test is free and usually nails it.

👉 Question for you: When it “bucks,” does the tachometer flick at all (jump up/down slightly), or does it stay steady? That’s a strong tell between engine misfire vs converter shudder.

 

A “cruise-speed stutter” in that 50–60 mph range on a 4L60E/4.3 combo is a classic gremlin, and the trick is figuring out if it’s engine misfire, fuel/ignition dropout, or torque converter clutch (TCC) shudder/slip.

Here’s how I’d break it down:


---

🔎 Common Culprits for Your Symptoms

1. Torque Converter Clutch (TCC) Shudder

The 4L60E locks the torque converter around 45–55 mph under light throttle.

If the TCC solenoid is failing, fluid is dirty, or the converter itself is worn, you’ll feel a “buck/stutter” as it tries to engage/disengage rapidly.

Usually no code is set.

Test: Lightly tap the brake pedal while cruising at the speed it acts up. If the stutter instantly goes away when the converter unlocks, it’s transmission/TCC related.



2. Secondary Ignition Weakness

Even with a “recent tune-up,” weak plugs, wires, cap/rotor, or a coil that only acts up under load can cause this.

At cruise, the engine is in lean burn — any weakness in spark shows up here first.

Test: Spray bottle mist test at night over plug wires/cap, or hook up a scope if you’ve got access.



3. Fuel Delivery

Even with a fresh spider, the pump or filter may be borderline. The CPI/Vortec injection is touchy about pressure (55+ PSI required to start, ~60 PSI preferred).

At steady highway speeds, if the pump can’t keep up with injector demand, you’ll feel a drop-out.

Test: Tape a fuel pressure gauge to the windshield and watch it while cruising.



4. Sensor Dropouts (less likely but possible)

TPS or ignition module intermittently cutting signal could mimic this.

But usually you’d get a code or more erratic drivability.





---

🛠 What I’d Do in Order

1. Brake-tap test at cruise → rules in/out TCC shudder instantly.


2. Fuel pressure check at idle, rev, and under load/cruise.


3. Double-check ignition (swap coil, inspect cap/rotor, wires — cheap insurance).


4. If trans issue confirmed: consider new TCC solenoid or valve body cleaning; worst case is converter wear.




---

My Gut

Given your description (“no codes, fine accel, fine idle, happens mostly at steady cruise”), I’d bet torque converter clutch shudder is the leading suspect. The brake-tap test is free and usually nails it.

👉 Question for you: When it “bucks,” does the tachometer flick at all (jump up/down slightly), or does it stay steady? That’s a strong tell between engine misfire vs converter shudder.
[

Wow, thanks for the breakdown there! As for the tach, it’s hard to tell since I have the digital dash, so small fluctuations in the RPM go unnoticed.

I’ll give it the break test, but normally I notice that if I gun it or let off the gas it tends to go away, plus as I drive it more after sitting for a few days it tends to go away.

I just did an oil change at a garage two days ago (can’t beat $50 and no oil spilled all over my garage floor from the relocated filter) and the garage pulled the trans dipstick and mentioned it was dark. Not beyond repair, but dark. A friend of mine had mentioned the torque converter lock up could be causing issues and recommended a fluid and filter change, plus a few ounces of Shift Restore transmission cleaner for good faith.

This weekend I plan to pull the cap and rotor and replace anyway, I have the Duralast gold on there now with lifetime replacement, so might as well get a new one for free. I’ll try the mist test and the fuel pressure test this weekend too. Plan on replacing the fuel filter anyway because I’m sure it’s well overdue.

 

Another easy check is the rotor and dist cap. My 01 Xtreme had intermittent misfire and it was a loose rotor. Years ago in another Chevy I found a melted down rotor causing bad misfire.

 

Replacing the distributor cap and rotor will fix this - guaranteed.

 

Replace the distributor cap and rotor and the bucking will stop

 

Bet you a dime to a donut it will be a loose coil wire.
Take it off from both ends and push it down hard on the cap and the coil. I like those blueberry cake donuts the best.
Good luck!

 

Does it ever out right die on you, I had the stutter but would give out completely. Then heading up a driveway it just gave out , shut right off. We had a bad wire on the crank position sensor and changed it, fixed the issue. I would get it hooked up to a good computer and see if you get a stored code but they're not crazy expensive. ( the sensor) my Kost hooks it up for free.Good luck!

 

Hasn’t died on me since the EGR cleaning and screened gasket, not that I remember anyway…I’ll take a look at it though!

 

One thing I would like to mention, the buck isn’t continuous when it happens, it’s sporadic and just a split second I can feel it in the seat. It’s almost like there’s a trailer hooked on the back and it’s weighing the truck back, as if hitting a bump or something. If that helps any pinpoint the feeling of the stutter it has

 

Spark Plugs, wires or coil packs

 

Might be fuel pump…left me stranded at work today. Relay clicks, no sound from the tank and no pressure at the rail when I press the Schrader. Towing it home tomorrow, any tips on fuel pump replacement?

 

Get an AC Delco pump. Not a fun job on a rust belt truck. Make sure you do the fuel filter, too.

 

Has the O2 sensor ever been replaced? They can get sluggish with age, especially during lean burn conditions like when you're cruising on the highway.