Hello. I just recently purchased a 2000 gt. I got the car for a steal. The modifications include a cold air intake, bbk throttle body, and headers as far as I’m aware. I just purchased yesterday the previous owner stated every now and then a check engine light comes on for running rich, p0172 and it did yesterday. at idle the motor is quite shaky. I’ve come to the conclusion it’s misfiring but not enough for the car to flash the CEL at me. Would a misfire cause the running rich code? The coil packs are all accel yellow coils. I know the typical things to check, coils/plugs/fuel injectors. Just wondering if there’s any other thing particular to these cars that is common to cause a misfire. It seemed to run fine when I was driving it down the road, it would hiccup every now and again going up a hill in low rpms. the worst shake is at idle which usually means it’s misfiring. I’m not leaning towards the coils because they’re newer accel coils.

So come to find out, the entire passenger side of the engine isn’t firing.