I noticed my LJ is sagging pretty bad in the back. It has a pro comp stage I 4" lift on it. If I'm not mistaken the coil height on a 4" lift should be around 16" in the front and 12" in the back. The front is about right, but the back is measuring around 8.25" and the shocks seem to have taken a serious beating in the back. What might my problem be? Crappy lift? What do I need to do about it?