With all this mention of "clunking" sounds, I would seriously suggest suspecting the suspension springs. They can break (actually, there is a known problem that Ford will not admit to) and still allow your car to remain at or near stock right height. Jack the car up, remove both rear wheels, and yank on the springs. They should not move in their mounts. If they do, you know they are broken. Even if they do not move, they could still be broken. Because of the design of the springs, it is hard to see the top (where they usually break) to tell if they are still in tact.
