Hi.
I have a 2008 mazda 3 2.0, ive installed a cold air intake and an aftermarket exhaust system. I have the check engine light (P0172..running rich bank 1) how do i fix this?..............I've replaced the MAF, bank 1 02 sensor and the EGR valve also cleaned my throttle body and my aftermarket filter. PLEASE HELP!!

 

running rich could be a leaky injector, or a bad/leaky fuel pressure regulator, weak spark... start there.

 

Check and clean/replace the spark plugs

 

Spark plugs would definitely be my first go to. The injectors are really a pain to deal with, so you definitely don't want to start with those.