88 xj death wobble

I have a 88 xj (that is at stock height and 225/75/15 tires) that when I hit a bump on the thruway it starts shaking real bad. It only happens when I hit the pothole around 55 MPH. I can drive down the thruway at this speed and everything is ok until I hit a pothole. It goes away and soon as I slow down to under 55 mph. I changed the front tires to 215/75/15 tires and the problem is still there. Any help is appericated.
Thanks, ED

I had the EXACT same situation and problem same size tires same year same everything.. people were shocked that i had death wobble at a stock height...

I dont have it any more!

New LCA bushings... Replaced half the UCA bushings the ohter half in the axel i wasnt messing with... and new why am i drawing a blank ... new bushings on those things that are visiable in hte wheel well.. umm the things that are uh verticle and about the size of a dog bone..

anyways that was 2001 no death wobble sense