getting some bad vibes after hitting bumps

I'm new to Jeeps so I'm not real sure what's going on here. I just bought an '01 XJ a couple months ago. It has 150k on it, 31's, and a 3" BDS lift with tcase drop. If I hit some hard bumps/pot holes at a decent speed, like above 40mph, I get sometimes get a really heavy vibration that continues until I lay on the brakes and slow down. I'm wondering if this is due to the lift or is it something worn in the front end? I haven't had a chance to inspect it yet. The only other vibes I get is at about 45-50mph from the driveshaft since there's no SYE. Thanks of any suggestions.

Does it have the stock track bar? If you have the C 8.25 rear end, I'd highly suggest getting rid of the Tcase drop and going with an SYE....

Sounds like what you have is "death wobble" - could be caused by anything, but a lot of times, the track bar (frame side mount) will be shot, especially if it is still the stock one....that ball joint type frame mount sucks. But then again, it could be anything from bad TRE's, bad ball joints....the list goes on....

A little late, but....I had this on a 95 wrangler and could not find any problems with the suspension or driveline anywhere. Around that time, I needed new tires and replaced them and the vibration was gone after that. I heard somewhere that the steal bands inside the tire can break and cause it. Anyway; my vibration was the tires.

I actually have the same vibes as described here but I know its just when I dont check my control arm bolts for a while. The upper control arm bolts that go through the axle get loose and that happens

check your steering stabilizer replace it and your problem should be fixed.