Is it normal having a little less steering assistance in low RPM's?

Should assist more at slow speeds. To check for belt slippage turn steering all the way one way, engine running in park, hold over for a few secs. if belt squeals, replace also check tensioner at same time. If no squeal pump or rack could be bad. Take to shop get PS pressure check to find out which. May need flushing but haven't seen where car would be hard to steer unless fluid looks like mud.