So does it also do the same on your stock wheel and tire setup? You mention that the low pro's are rubbing. Do you mean the tires, or the actual suspension?

My best guess is that you need new shocks for your ride (I don't know if you do have aftermarket shocks, you failed to mention it). www.groupbuycenter.com is a good place to find some aftermarket shocks for your ride.

Although this might not be your problem, it could be a factor. Others might be able to elaborate on your dilemma.