park the car on level concrete floor, make sure all 4 tires have the same air pressure, and measure from the floor to the frame at the 4 jacking points.
if it measures out ok here, then the problem is with the body. keep measuring to different reference points on the body to see where it's tweaked.
if you get different measurements at the frame, then unhook the front sway bar and see if that changes anything. do the same with the rear sway bar- it's really easy to bend it if you aren't paying attention when jacking up the back of the car, and that might put some twist into things.
you could also remove the shocks and see if it levels out, too.