Need help. Gave my 94 Z-28 to my son, it has 35000. He is driving to his new base cross country. Engine started running rough when he tries to accelerate. I had all fluids drained/flushed and all rubber lines replaced. New fuel filter, plugs, wires and had the injectors cleaned at a Chev dealership, Over $1000 and no difference. I assume they checked the fuel pressure and the OBD for codes. I'm down to MAF or Optispark. Hard to diagnose from 1500 miles away. Any thoughts?

 

Sounds like your on the right track. If its throwing codes I would get that checked first instead of buying unneeded parts. 1500 miles away your best bet would be to get him to take it to a reputable dealership in his area.

94 Z28 A4 known mods... reworked ported heads/intake. Cam, 3" cat back flowmaster. unknown PCM tune. still researching car. ...

1990 RS HO 305, TH350(shift kit). 4 barrel carb, Cam, Long tube headers.

 

Has the ignition control module (ICM) been checked? Has the coil been checked?

 

More info: I think (hope) we figured it out. Last bill from Chevy Dealer says "found injector driver in PCM loosing signal to injectors causing misfire". They told him they don't work on PCM's older than 2000. Lots of PCM's on line for around $140