Loud hum in 95 Explorer
 

Hey all! I just bought a used 95 Explorer that is super clean and in great
shape. I noticed that when I start the car, whether it be warm or cold,
and intermitently, there is a loud hum that doesn't go away until I'm
actually driving it. For the life of me I can't figure out where it is
coming from. Any ideas? Thanks in advance!

Well, now that I've done a little search here using keyword "humming", I
see I'm not alone! I think I have a better idea now of what might be
causing this. If anyone has any other ideas, please, let me know.
Thanks! :)

at idle the hum is from the iac 60 dollars and replace it.