89 suburban steering problem

[mygirlz55]

Hey all, I have an 89 suburban 4wd that I'm having some problems with the steering. While driving down the road, when I turn the wheel to the left or right and then come back to straight, the steering wheel isn't always in the same place.
I have looked at all the steering and front suspension parts and can not find anything loose. The steering wheel is fine, not spinning on the shaft.
Is this problem due to the power steering pump being bad or the steering gearbox being bad? It also seems to be more movement of the steering wheel needed to make a turn. It isn't hard to turn, just have to move it quite a bit.
Thanks in advance for any help.