Need some Suspension Advice Please....

What's the rear suspension? SS springs, Calvert etc. Weight, trans, tire, air press, etc.

Can be a couple things. If SS springs don't move the snubber closer. Make sure no bind in anything in the rear. If you have adjustable rear shocks tighten the extension, and/or make sure they are not overextending. It sounds like the car is "porpousing".

Also do you have 4-5" of free travel in the front end with no bind etc?

Hopefully a place to start.