I have a 2001 F-150 4.6L. Recently I have been hearing a strange humming noise (almost like something has a bad bearing) at idle or slow speeds no throttle applied. Checked engine- all looks fine, but noticed the air intake is vibrating. Took off air duct at filter, choked out the intake with hand- engine starts to die - let it have air and vibration and noise are gone. Start driving and it comes back. Cleaned air filter checked all clamps and such- Thinking it must have something to do with throttle body but really dont know where to start. Would love some suggestions on my little problem. Thanks

 

Welcome the the forum. It is usually the IAC valve that makes the noise.

 

That was it- Thank you very much for the help!!

 

No problem!!