New Rear Suspension setup questions??

Ok guys I have an 89 mustang that I just upgraded my springs in the car. The car currently has Ford Motorsport Rear Upper Heavy Duty Control Arms and the Maximum Motorsports Rear Lower Control Arms and the springs that I just put in are the Eibach Drag kit Springs. The car has sub frames, 6 point roll bars and new battle boxes just installed by wild rides. Now I took out the out the quad shocks and the car was fine while I was doing a burn out. So I took the car to the track with slicks and I got like a 1.47 and 2 1.5 sixty foot times (with absolutely no wheel hopping what so ever) and now the other day I took my car out for a spin and before I put the car away I did a little brake stand/power break with line locks and the whole rear end was hopping like crazy, it was so bad that I could see light out from the hatch. Now do you think that one of my components are going bad or do I just need to put my quad shocks back in. I really didn't want to put them back in because they tent to hit my slicks but if it helps the hopping out then great.

Please let me know what you guys think

Website for car with mods

Thanks
Nick

Yea at the track with the slicks everything was fine. I did a burn out in second gear with no wheel hopping at all and if i look back at the tapes it there rear doesn't even bounce. I have 373 gears. It just seems weird because I was able to spin my street tires without and wheel hopping like 1 month again and the car only has about 60 miles on it since then and that was miles just driving to a couple of car shows. Yea my car is pretty level and maybe the front is a little higher becz of the drag spings. I got tokico shocks all the way around. I am going to look in to the springs tomorrow and open the rear to make sure everything is fine because i need different shims in my rear. The whole things is just weird becuase it was working fine and then bang it started acting funny. BUt i will keep you posted and let me know if you think of anything else.

Thanks for all you help.
Nick