2000 Park Av power steering

There are times at low RPM's that I lose power steering and its very hard to turn the wheel. A typical situation would be turning into a parking space where you slowed almost to a standstill. My mechanic told me the car doesn't have a pressure sensor that would advance the RPM's to maintain ease of turning the wheel. He cleaned linkages and did a $100 worth of other work and it seemed to help a little but the problem persists. Anyone have any helpful suggestions? Thanks

I wonder why your mechanic did not replace the pump?

Wow, hope it's not the rack???