I have a 98 mountaineer AWD, 5.0 that whines horribly with increased/decreased engine speed. Even at idle. Used a stethoscope to try and pinpoint location of noise, sounded like alternator. Replaced that with an OEM one, but problem still exists. Anyone have any experience with with this problem? Thanks for all your replies! -Sunny

 

Ususally a Ford whine is in the Power steering pump.
At idle turn the steering wheel, if the pitch of the whine changes.. that's it. (in most cases)

 

check the:
idler pulley
power steering pump
the serpentine belt may be glazed, replace it with a ford belt.