power steering problem

--------------------------------------------------------------------------------

I just purchased an 2002 4.2 with 47k. The power steering works fine at low speeds but at highway speeds it gets very tight, so much so that you have to really hold the wheel firmly. It is almost as if the P S goes out entirely. When I turn the wheel it does not return to center and stops at 10 & 2 o'clock. Is this normal? Any help would be appreciated.
Chip

 

could be one of your drive arms or a component of the power steering