1992 Chev. Lumina 3.1 L

I had a power steering fluid leak from the low pressure cooler line. I cut out the rubber portion of the line that was leaking ( crimps from aluminum to rubber ) and installed a new rubber section on line using hose clamps. I refilled power steering fluid and ran engine. No abnormal noises and leak was fixed.
Now I have noticed the power steering is inoperative at idle. As soon as you increase engine rpm's, the power steering works normal.
Prior to the line section repair I did not have any issues with the steering, only the leak that was repaired. The pump/rack was never run empty.
Any hints on where to start and diagnose this???

Air in the system is one possibility,. another is debris got into the system during the repair and could be stuck the pressure relief valve in the pump.

UPDATE:

Confirmed fix: Power steering pump replacement

Checked pressures and found pressures below specs. Flushed lines, rack and replaced pump.

Thanks for the post