[TwEeKeDStang]

Not to make it sound like I think you're an idiot or that I AM an idiot (by all means I may be) but did you do anything to the computer? I know these 90s stangs dont deal well with mods (even just exhousts) and can cause the engine mod not to work properly. I know I had to do that when I added new headers. Check that out.
Also, I also had the engine light problem (before the computer) and it could also be the O2 sensor, or could just be a slipped belt. Those are two previous reasons for my engine light to go off. Also, speeding at 115 and swerving from a pot hole made mine go off... as did the old joke, "Check engine?... Engine, check." And closing the hood... yellow lights piss me off...