Power steering pump or something else???

I have an 89 trooper 2.6 w/ auto trans. This sounds weird but the power steering is freaking out! Sitting still, it turns fairly easy to the right but it is hard to turn to the left. When driving down the road, it turns easy to the right, but harder to the left, It drives straight as an arrow going down the road. when you make a 90 degree turn (either direction) it wants to pull hard to the right for a short distance, then it clears up and goes straight. It's not making any noises that I can hear. I did replace the belt since it was loose and worn. It helped a little bit but did not clear up the problem. Any suggestions???

By the way, it has very little to no play in the steering wheel.

OK.....................I GIVE!!!

I put the post up right before I left the office. In my 45 mile commute home, I did not experience a single incident of this crazy steering problem! Maybe it had a piece of rubber hose or O-ring caught-up in the pump somewhere and it cleared out. It is 20+ degrees warmer now than it was this morning but that shouldn't matter. Anyway, it's working fine right now. I think I'll flush the system this weekend just for piece of mind.

Make sure you get all the air out too.

I'll definitley be flushing it out this weekend! It appears that my power steering still wants to taunt me! I was almost to my office this morning (45 mile commute) and it started freaking out again. Oh well............