I have a 97 4x4 that is having a steering problem. Occasionally the wheel will force itself to the right for just a second. It does this in a rhythm. It doesn't do it all the time. It almost seems like the power steering is fighting me.
I just took it off the road for a while and the undercarrige got fairly covered in mud, so I don't know if that could be it. I'm not very framiliar with the power steering so I don't know exactly what could be wrong.

 

look in your rims. if theres mud in there, spray it out. drive the truck and see if that fixed the problem. if it doesnt, take your truck to a trusted tire shop and have them check your front tires balance. you might have thrown a weight.

 

The weird thing is it doesn't do it all the time, just every once in a while. I sprayed the wheels, and it still does it, but it seems to be less severe than it was before. It also happens less often now. I'm hoping that it will go away with a little more driving.