2000 Dodge Durango powersteering problems

Hi Jacobandnickolas,
I've bled the system three times and still have the same problem. Also changed all the o-ring seals several times along with new fluid and replaced high pressure line and return line. Second new pump today, same thing. Start the vehicle, turn the wheels and the fluid bubbles and foams out of the reservoir, growls very loud. If I put the cap on when this happens it will over pressure so bad that it will blow fluid out of the cap seal. I'm wondering if it might be a bad rack?
Thank You very much for your help.

The original pump did the same thing, just not as bad. I assumed (i know bad thing) that it was because the original pump might have been worn out, and the new pump was putting out full pressure. The wheels will also shudder about 1/2 to 3/4 of a turn before the left and right stops. I was a certified mechanic for many years, but I haven't done any work in a shop in quite a few years. I mostly do my own cars now, this is for a good friend of mine. Give me the old cars any day.
Thank You