The rear end on my 1990 RS sways to the right when at hwy speeds and tapping on the accelerator. I've replaced the pan hard bar, and rear control arms. Thought the new phb would do the trick. Is there something with the torque are that needs to be addressed? Is the rear axle wore out (there's no noise from it)? At a loss on what it could be.

 

worn shocks, springs check sway bar bushing and mounts also need to be check , on my RS had a swaybar mount broke at the bolt , also you should thighten them with weight on car because it will bind

 

The alignment on my car was great from the time I got the car up till I got new tires on it. Since then the rear end feels like it's moving out from under the car and it pulls to the right.
Everybody says to move the tires around. Which might help with the pull, but I think the rear is a mechanical issue.

 

If the only thing that has changed is tires I'd start there. It takes 15 minutes to rotate the tires, just do it quick and see if the pull moves to a different side or something.