my truck is a 99 F-150 4.6L auto trans. and the Engine is running really rough, and starts randomly backfiring. I pulled the Code P1504 FORD - Intake Air Control Circuit malfunction. but dont know what it means or how to fix it any help would be great, thanks.

 

Idle air control valve is most likely just gummed up with carbon. The IAC is on the throttle body. 1 plug, 2 bolts. Remove, clean with TB cleaner, put back on, clear code and enjoy.

I'll see if I can find you a picture of it so you know what the perp looks like.

Okay I stole the pic from another forum, so ignore most of the writing because it isn't mine lol. The IAC is pointed out in this pic