[Ken in MN]

Hi,
After replacing the ps pump and and steering gear box, I noticed that the steering is easy when the car (and pump) is cold but gets increasingly more difficult as I drive. It's almost as if I have very little PS pressure when the pump is hot. It's almost impossible to parallel park - it's that stiff.

Also, when this happens, the pump gets too hot to touch. How hot should it get?

I'm using PS fluid in the system. Would it make a difference if I switched to ATF? If so, which brand of ATF should I use?

Suggestions?
Ken in MN