We have been fighting this gremlin for some time now. The car now starts great, thanks to a new fuel pump, and idles great. The miss starts under load, it can be light or mid throttle or just crusing. Under WOT it does not appear.

Things that have done to rid the problem: ignition module, cap, rotor, wires, plugs, fuel pump, and most recently the injector spider. I have run out of ideas, PLEASE HELP!

Clint

 

It would be helpful if you posted your vehicle info.
Have you check for codes and if so what are they?

 

DOH!! I guess that would help huh. 1997 4.3L Vortec "W" code motor - No codes,.

 

This is mostlikely caused by the EGR valve opening/closing. It may not be something that can be corrected, but under the right conditions (i.e. the A/C compressor engaging and the EGR valve opening), it may feel like a missfire, when it really is an unrelated convergence of normal occurrances... Ok, sorry... I just confused myself there, LMAO. At WOT, the EGR valve closes and the A/C compressor disengages.

My Bravada did this same thing and I know that the truck was in tip top condition. But this was something that I could feel, but NO ONE else that would drive it...