From my experience with the 97-03 gp's, It's usually as you said, simply the sensor that does this. If you have time, check your sensors to make sure they are still all connected. I was able to just reach behind the tire and check mine but I had changed them a few times so I knew right where to feel. I'd say to get under there and give her a peak. If they are hooked up, one may very well just be shot. I don't know if anyone on here has found a way to replace the sensor itself, but I've had to change the whole hub when it happened to me... lol
as far as power steering issue, can't help you out there.
ps. Where you from in Niagara?