Jeep "Death wobble"??

I have a '99 Jeep Cherokee sport 4x4 with a 4'' lift on it. I bought it from someone that put the lift on it himself. It drove great at first but now if I hit a bump it sometimes gets this intense wobble back and forth thing going on. I was told that the drivers side front sway bar has a gap where it connects. They recommend that I shim it. Any input on this would be greatly appreciated. THANKS!!!