Hey everyone, I had a strange thing happen this morning when I was parking my truck. I pulled up to a parking spot and when I stop to shift in to reverse to back in I noticed my head lights dimmed and the rmps dropped when I put the transmission in neutral. When I put it in reverse the rpms came back up and head lights brightened up also. I did this a few times and it was consistent every time. Same behavior from neutral to drive as well . Is this a common symptom of IAC valve? By the way I have a 2003 F 150 5.4 liter with 136,000 miles on it.

 

i had a similar issue with my 01 but mine would stall out some times. after a few days of getting pissed i looked under the hood and noticed that my strap on my air box broke and the air box was seperated and hanging down. after i put a new clamp on i worked great