engine squeel on 2007 Ford Explorer Sport Trac

I own a 07 Ford Sport Trac that has a squeek that comes and goes,sometimes last for a month then goes away for a few then returns. I have replaced belt tensioner - pully -water pump - altenator - and am getting ready to replace power steering pump. I am running out of money and patience, any help would be great.

Asked by for the 2007 Ford Explorer Sport Trac
There is a bulletin for this concern. This site is for Mustangs, but it applies to your vehicle.