What are signs of the two? I have anoticed a little drop in acceleration power and a little bit of a gas smell (that may not even be my car). Of course I have carbon build-up on my tips and rear bumper but not as bad since I installed the new O2's with the headers. Could these two cause any such problems? What would a crappy coil do? Also I did the IAC reset I found on Shoeboxes' site and I have not drove it since I did it. Thanks for any help/!