So I have a 96 S10 with the 4.3 which isn't tunable. I installed the PCM out of a 99, it's setup for the same 4.3 engine and everything. After removing VATS it starts up fine but is misfiring on two cylinders. Oddly enough a second 99 pcm which I reflashed is also misfiring. Is this just a massive coincidence or is there some small difference in engine wiring between the 3 years that would cause that?
