My brother just bought a 94 Z28 with a few modes, one of which is a cc304. How can you tell if the programming is stock? it seems to stumble and backfires every now and then and eveything else checked out ok.

 

i ran a cc304 for a year on the stock tune. No backfire, no stumbling. I would get the occasional pop when revving in neutral cuz of the gutted cat.

I dont know much about programming, i would imagine that you would need to download the program from the pcm using a laptop, obd1 cable, software, and do the same on another pcm and see if the programs are the same ??