I am get a humming noise from my truck (2001 F150 V8 5.4L) after I have driven it for awhile. It happens when I am in park idling. What could this be from?

 

you need to replace the IAC valve

 

Not to sound ignorant, but what is an IAC valve?

 

Idle Air Control Valve

 

The person that had it before you might have removed the intake silencer. It will make a low humm at idle when it's gone. The silencer is a plastic tube weged into the fat blob of your intake tube.

 

IAC is located right behing the throttle body, do a search for pics too and details about cleaning it. A humming noise usually isn't good, but try a good cleaning and see how that works. There is no shortage of IAC info, especially lately so search it out some.

 

Thanks, for the info, I will look into that