I've got this whining noise that is only heard when engine is warm from 1900 to 2500 rpm. If got a 2000 f-150 5.4L I removed the belt and started it warm and theres no noise. Its also got a ruff idle but is not there when the belts off. All the pulleys spin fine except the idler but i wd-40 ed the crap out of it and spins fine now any Ideas?

 

If you had to spray the idler replace it,the bearing is bad.Had one on Ford van go out and thought it was the Alternator going out.