GM-GMC: power steering ????, 4wd club, alignment problem

Question
 Have 2003 s-10 4wd club pk up with a wander problem. The steering parts all ok and dealership said I had an alignment problem. They did an alignment and problem is still there. I do not care to go back and donate my money anymore. The steering has 0 play and when driving it does not want to go straight.It will go left or right and when you correct it very slightly it seems to over react and I am constantly corecting.Could the power steering unit be over assisting and do you have any suggestings?  Thanks Pete L.  

Answer
Yes, the problem could be in the power steering system and might be the steering box itself.

The other possibility is a tire with a slipped or separating belt.

You might also want to get a second opinion about whether the alignment was done correctly.  If the caster is set incorrectly, the tires won't wear improperly, but the steering will be affected.