all work done on my 1990 gt. i just replaced my injectors they are 24s and my maf is calibrated for 24s i also replaced my throttle body with a bbk 70mm the car will start fine and idle fine at first then when i was driving the check engine light came on and when i down shift or let the rpms drop it will back fire real bad and when i stop the idle drops so low it will barely stay running. I have a b cam and when i removed my stock throttle body it had a hole drilled in the throttle body blade from the previous owner could this have anything to do with it?