Hey so i have a 89 fox body lx 5.0 ho and i have an aftermarket a/c unit and flowmaster exhaust but the mufflers have pipes in place of them. My car will throw a check engine light randomly and it seems to be when i decelerate from around 2k rpms and sometimes it goes away at idle aswell. I dont know if its from the aftermarket a/c unit, that whens i started noticing the light, could possibly be vaccum? im not sure. but i also read that more free flowing exhaust could do that too but i still have the cats in my car. if anyone has tips on what to look for would appreciate the input, thanks.