Fellow GM Guys: I have been having trouble with my 1996 Buick Park Ave when going up a slight upgrade on the highway and stumbling while at a light load @ 1500 - 1700 RPM. I'm looking for any additional ideas in what to check.
Here'* the history of what'* been done - Found that two of the coil banks where missing, so I replaced the Ignition Module and all three coils, Plugs (NGK Iridiums) are only 15 months old, wires replaced about 5 months ago, fuel pump and fuel filter replaced about 7 months ago, cleaned the MAF, checked and cleaned the EGR, replaced the PVC about 2 months ago.
Latest: I found that one of the plugs was missing when revving the engine to 1500-1700 RPM - replaced the plug, but now others are missing. I've replaced all of the plugs with Bosch 9601 Iridiums, and found that the NGK'* gap has increased from 0.060" to 0.062". I understand the Bosch plugs are a hotter plug then the NGKs.. I gapped the Bosch plugs to 0.060" - required gapping out of the box... So far, so good. I'll keep you informed.