Dose the rpm change only when you are turning?
Dose the squealing happen only when you are turning?
If that is the case my guesses would be loose belt, oil on belt, weak idler pulley, bad power steering pump or Brg. ( I don't have the 5.2 so I'm not sure if the idler pulley is spring loaded)
Let us know what you find out.
Wish I could be more helpful.

 

I'm talking when they rebuilt the pump at the reman-factory not at the auto parts store.


Back to the issue your having because you said it happens while turning right?



Master is talking about removing the belt entirely just to see if it's the motor or what, only do this for a second or 2. Also while the fan belt is off grasp the pulleys and rock them to see if you can feel any play.

 

i agree with what hydra and master tech suggested, try it w/o the belt on (dont run it too long) and see if you still hear the sound(if the sound is gone then the problem HAS TO BE one of the pulleys, or appliances driven by said pulleys)