OK guys, my exhaust system on the car was 2 inches when i bought it, just had a tanabe dp,and a catback exhaust system put on it. The car was super slow and you could hardly hear the turbo before, now it will blow off in neutral, but when the turbo kicks in it sputters, im guessing its my afm, and its bad, i just replaced the 02 sensor. Also the car is spitting black smoke out, which means its running rich, is this all because of the afm being bad or is it even bad? If so how much and where could I find one?