The truck does NOT use the narrow band o2 sensors for WOT.

 

Those of you that have found and or repaired the problem I seriously beg of you to post the solution. I have the same issue and have followed all the diagnosis posted +wires, cap, rotor, plugs and a different (not new) mass air. My last resort is changing the distributor but I'd really like for someone that changed dist to cure issue to explain what kind of failure they found in theirs before I throw a couple hundred bucks at a hope. Thanks any insight is very appreciated

 

I also ask for any updates/solutions....my 95 is doing exactly what the op described, exactly.

 

The 95 is different from a 96+. Lots of problems have the same symptoms and the ECU is terrible a diagnosing so its usually about useless. I would check timing and the fuel system first. Those are common problems, especially with fuel.

 

Check Ur Coils... this will cause stumbles, backfiring and poor acceleration, Even if you replace the Ignition plug wires, plugs ,cap and rotor.... did you happen to notice that the coil tower lug is still attached to old coil wire? Found many 4.3L GMC/Chevy that ended up with this issue. Folks replaced wires/plugs/cap/rotors/spider injectors/fuelpumps and never even checked the coil..Wish I could just start replacing parts and charge all my customers for them. When you get a repair bill that has a lot of parts replaced to solve a problem you took it to them for, 9 out of 10 it was usually a person that just part swapped at your expense till the problem was fixed so ask him what last part he replaced that fixed problem and tell him that's only item you will pay for and labor to install it...Love hearing about how someone took in for misfire and got billed for tuneup , Ignition module, Distributor,fuel filter,fuel pump,cam sensor and coil... all replaced which so called causing misfire????? NOT...Check the basics above all !Now taken to have a vehicle tuned up yes plugs/wires cap and rotor that should be all due to cars being ECM timing controlled so no adj timing anymore. Best to ensure you either ask to see all old parts (due to some having core charges) or demand up front when dropping off vehicle you want all old parts replaced that didnt have core charges that way you keep mechanics more honest and they don't bill for replacing parts they didn't.