my 02 f150 recently started making a humming noise coming from the air box, i work at a ford dealership and everyone told me it was the IAC cause it idles weird when it does the humming noise. Put a used one on it which was still good from a buddy’s truck and it never did it to him, and it started it again. I thought it was my cheap cold air intake and i Just replaced it back to stock. And it’s still doing it. Affraid to buy new IAC and it’ll do it again and it would be waste of money

 

Andy, why don't you get in there and find the cause instead of just changing parts driven by guessing.
There are rubber parts on the intake system that likely have gone hard and split open.
A dealership employee and they can't help you better than this such that you have to come here for help?
You must have a lot of friends their.
Good luck.