On the last 3 vehicles that I diagnosed death wobble on it was the pan hard bar axle side bushing that was the big culprit. Have you had someone sit in the vehicle and turn the steering wheel back and forth while you looked under the front end? This is how I always find it. Put your hand on each component and watch each joint to find the one that has slop in it. The outer hole on the axle side pan hard bar bolt gets egg shaped and typically allows the front end to move around. It can be caused by any number of things though. A quick fix for the pan hard bar issue is to weld the correct sizes washer to the axle, effectively making the hole round again. Just did this to my old roommates Jeep on Friday and he said his drive home was much more enjoyable than the drive to my house.
88 YJ with a 4.6l stroker, AX-15, NP231, 2.5" lift, 4.10's and 33's
2000 Red XJ w/ 350k+, AW4, NP231, Locked Rear, HD Crown Leafs, trimmed to fit 33's, soon to be a donor
2000 Silver XJ, Drivetrain from the Red XJ, Stiffened, IRO leafs, RE coils, custom 3 link, WJ knuckles, 35's <=== In the works