Power Steering Problem...

This is on a 2000 Grand Prix GT...
Was going around a corner about an hour ago and the power steering just gave out for a split second.
What happens is it turns perfectly fine going right but going left it gets tough in three spots. Basically a half turn after going from fully locked right to center then another half turn going from center to fully locked left, but inbetween these spots it's perfectly fine. The third is when fully locked left. The release valve doesn't sound and it's really tough to get it to fully lock.
There seems to be no leaks that I can see, yet, but the PS fluid was a little low. Nothing drastic, just a little below full-Cold (on a warm engine) so I filled it up to right below full-Hot. That didn't fix the problem.
So did some searching on the net and came up with this:
After reading about the pumps putting out more pressure at higher rpm yesterday, leaving work, I reved my car up to 2500 rpm and worked the wheel left and right a few times and the left freed up. Now it was steering like it was before the problem, not great but acceptable. Still whines a bunch. Later that evening about 5 hours later I was leaving a place after being there a couple of hours and it was hard to turn to the left again, so I did the same thing and it freed up again. This morning I get in the car and it is fine. Wierd. Can the PS fluid get gunk in it and clog up the valves in the steering rack? With 120k on the thing is the pump going out? Should I replace it before it grenades, or should I just flush it out and try fresh fluid? Do I have to replace the rack if there is nothing wrong with it, I assume no.
So went out reved the engine to around 3K while sawing back and forth, it freed it up completely at the right->center problem, the center->left problem is still slightly there but not as bad. Fully locked left it didn't help at all though.

Anyone dealt with this problem? The pontiac dealer around here is practically worthless for fixing anything so I don't want them to touch it and I'd rather do the work myself as it is...
What I was planning was to flush the PS fluid completely and refill it to see if this fixes it. Problem is that I can't do this for a few days. So, any help would be greatly appreciated...

I have the same problem kinda. I have a 2000 GP and i have a really hard time turning to the left when its not warmed up. When its really cold out, it take almost 2 minutes before my car will turn left with out fighting it. It turns right perfect though. I just bought mine a few weeks ago and it has 40K on it. IM getting it looked at in a few days, but i wanted to know if anyone knows whats up before i bring it in.

I have a 2001 GTP with 29,000 miles on it that did the same thing. I took it to the dealer and they found the the rubberish plastic cover on the rack and pinion was rubbing on the frame. It only did it when I would turned the wheel. I would look and see if that might be the problem. The dealer just changed the rack out, but the mechanic told that they did that becasue it was still covered under the warratny. He told me he had many cars coming in with the same problem. And a quick fix is to clamp that boot down, because over time they expand.

Guys, when that happens could be related to a worn rack&pinion assy. With time or severe use the rack and pinion could wear making the rack getting stock on certain places on its travel to the left or the right. If your pump has oil and the problem is to one side(The pump does not know to what side you are turning when delivering the oil feed) then most probable the rack&pinion or binding tierods(highly inmprobable, but not imposible)