How many miles on this car? Could be ball joints, tie rods, differential mounts, etc etc etc.

I would find a shop with a Hunter Road Force balancer. In my experience this is the best balance around. Google on Hunter Balancers and go to their website. They have a shop locator module. This machine will give you a printout for each wheel. It will also pick up any out of round condition on a wheel.

I would use the dealer for alignment. Your's is obviously screwed up.

As to the counseling about not going 80, my comment is that around Atlanta you had better be going 80 in the 70 zones or you will be run over.

My '92 Sportline with 230K is vibration free to all the way to 100. I generally cruise at 10 over the limit.

Steve