Tahoe bucks when accelerating at highway speeds but only once!

[iamdub]

I had an S10 that did this in various forms over the years. Never an SES light for it. '02 4.3, but same generation and design as your '96. First time was only during high RPM, like right before it upshifted during a WOT run. That ended up being the crank position sensor needing to be shimmed out (GM has a TSB on this). Years later, it would intermittently stumble and it was resolved by replacing the cap and rotor. This happened once every 1-2 years. I found that it was eating caps and rotors due to having an MSD box and lack of use. Basically, the rotor is like points in an old distributor and they're only good for so many arcs. An MSD has multiple arcs so the life of those components is shortened. The arcs cause tiny damages to the tip of the rotor and the terminals in the cap, so having a lot of them plus having it sit for a while (it wasn't my daily) allowed it to corrode more quickly than a stock, daily-driven vehicle. I removed the MSD and replaced yet another cap and rotor and never had the issue again. I used OE or Borg Warner parts on that one and they served me well.

Is that new distributor you have an OEM part? Or, if it's the upgraded billet shaft version, you might still need OEM or another comparable good aftermarket brand of cap and rotor.

Not saying this is your problem. It could be fuel, electrical, etc. Just sharing my experience to help you be as thorough as possible.

 

[exp500]

Do more Diagnosis. Fuel pressure tests, especailly at speed- use a long hose to put gauge on windshield.
Distributor cap- AC Delco/Delphi or United DCR-820x only.
Live data scans at speed when miss happens a big help.

 

[Tator]

I had an S10 that did this in various forms over the years. Never an SES light for it. '02 4.3, but same generation and design as your '96. First time was only during high RPM, like right before it upshifted during a WOT run. That ended up being the crank position sensor needing to be shimmed out (GM has a TSB on this). Years later, it would intermittently stumble and it was resolved by replacing the cap and rotor. This happened once every 1-2 years. I found that it was eating caps and rotors due to having an MSD box and lack of use. Basically, the rotor is like points in an old distributor and they're only good for so many arcs. An MSD has multiple arcs so the life of those components is shortened. The arcs cause tiny damages to the tip of the rotor and the terminals in the cap, so having a lot of them plus having it sit for a while (it wasn't my daily) allowed it to corrode more quickly than a stock, daily-driven vehicle. I removed the MSD and replaced yet another cap and rotor and never had the issue again. I used OE or Borg Warner parts on that one and they served me well.

Is that new distributor you have an OEM part? Or, if it's the upgraded billet shaft version, you might still need OEM or another comparable good aftermarket brand of cap and rotor.

Not saying this is your problem. It could be fuel, electrical, etc. Just sharing my experience to help you be as thorough as possible.

Thank you so much for the insight, I will have to take a look at the crank position sensor. However, the new distributor is in fact a OEM part (either delphi or ACDELCO from what I remember, will double check and report back if different). I think my problem is different from yours as it can happen at 1500rpm with anywhere between 30-60% throttle.

Do more Diagnosis. Fuel pressure tests, especailly at speed- use a long hose to put gauge on windshield.
Distributor cap- AC Delco/Delphi or United DCR-820x only.
Live data scans at speed when miss happens a big help.

Agreed, Im looking to borrow a scan tool here in the coming weeks to see if I can get any codes out of it. Especially if there are any transmission codes. If I can borrow it for long enough to get a live data report off of it I'll be sure to do so. I'm starting to suspect the torque converter is the culprit and/or the TCC valve/solenoid. Seems like others have reported issues similar to mine and that was the resolution... I realize now I have not checked my transmission fluid in a very long time. start with the basics, right? lol

P.S Anyone have any good recommendations for a diagnostic tool that can read transmission codes on these obd2 GMT400's? Outside of a tech2 as I'd like the cross-brand support and dont need any sort of flashing capabilities.

 

[Eman85]

You can pull the wires off of the plugs and take a look in the boots for any black marks, look at the plug porcelin for marks also. Easy to crack a plug or get carbon tracks. I'd pull the plugs if someone else installed them and check the gaps. A little dielectric compound (slicon grease) inside the boots works well. A poor man's scope is a spray bottle of water and a friend to lightly powerbrake the engine. While they powerbrake it mist water up each plug wire and see if it skips.