Changed the shocks, but when hitting ruts in the road, the rear hits hard. Has anyone had this problem before, I am thinking the springs need replacing?
Is your car lowered? If the stock bumpstop was not replaced with the lowering springs then I bet you are slamming down on that when you hit those big bumps. That was the case with my 95 GT when I bought it.
Check your bushings and torque boxes. Make sure they aren't ripped.
Springs really don't really go bad. They might sag, but they won't bang over a bump. Of course...spring could be busted. If you changed the shocks and still bangs, I would look under the car for something broken.