Sometimes the power steering pump makes noise and sometimes the steering wheel gets hard and frees up after a min . any ideas whats cuasein this?

this is an 1997 chevy s10 pickup Ls vin x

 

well, aside from the Power steering pump possibly being bad, there is a fluid orifice inside the PS pump that can be replaced. The ones from the factory are not large enough to account for gunk buildup over the years and the aftermarket ones have a slightly larger hole to provide more fluid to the pump. I had a similar problem with my 98 and it turned out to be the front passenger side axle falling apart and causing a binding problem when sitting still and turning the wheel.... Hope this helps