Every JK Death Wobble discussion immediately says track bar or steering stabilizer but for those who have the problem beyond these things, here is my experience and suggestions. So my 2 door JK had nearly 90,000 miles before Death Wobble struck. I had changed out the trackbar bolts within the first 5k miles so I thought I should have been good. Everyone immediately jumps to the trackbar bushing or bolt holes, and even mine had wallowed out the hole, BUT after repairing and replacing the trackbar and bolt holes mine still had death wobble. So that is when the really frustrating part began. Within that month I had replaced the entire draglink, entire tie rod and ends, both sets of ball joints, both sets of unit bearings, and had a professional wheel alignment and balancing. Yet the death wobble would still lurk and occasionally rear its ugly head. After 4 months of winter driving it became more prevalent with the spring potholes. So after googling and reading everything I could I had two options left. Replace the control arm bushings in the axle, or sell the Jeep. So I ordered up the axle side upper control arm bushings from Quadratec and spent a Saturday morning replacing them. At this time I also went from my winter tire pressure of 26 to my Summer pressure of 30. Then I took the Jeep to my highway test track where I knew it had forced death wobble and kept the Jeep between 40-45 mph for 15 miles hitting as many dips in the road as possible and I could not get it to shake violently. There was plenty of bouncing of the Jeep but no Death Wobble. I will still be holding my breath for awhile to see if it may be cured but for now things look promising.
So for those that have Death Wobble beyond a trackbar repair I would offer this suggestion to start looking for where your evil vibration may be. These are not in the order I fixed things, but they are in the order I would look at things to diagnose now. Any of these can contribute to the problem, but if you want to save some money you could check all of these things first and then see which one seemed the worst before buying parts and replacing things, then work backwards from worst appearance to best. I do not buy into theories that a steering stabilizer is a solution. Its job can help absorb the frequency wave, but on my other JK axled Wrangler I have never run a steering stabilizer and have never had Death Wobble. So a stabilizer is neither a solution nor a cause for Death Wobble.
1. Change your tire pressure whether higher or lower a few psi. Because the wobble is created as a frequency wave, the different sidewall height will change how the vibration frequency is sent to the rest of the suspension.
2. Check trackbar bushing and bolt holes at axle and frame for any loose fitment.
3. Check your tie rod joints, using a large set of pliers you can squeeze the joint from bottom to top and see how much play is in the joint.
4. Check your ball joints for excess play. Jack up one side of the axle to get the tire off of the ground and then use a prybar or pipe under the tire to see whether the tire has any up and down movement separate from the axle.
5. Check the upper control arm bushings by unbolting one control arm at the axle and look for wear in the rubber. Whether stock suspension or aftermarket, the bushings in the axle are often left original, so this is more common to be worn out than any of the other bushings which would have been replaced with most aftermarket control arms.
6. Check draglink joints- I don't think this would necessarily contribute to the Death Wobble but if you have been having Death Wobble that excess shaking could put extra wear on those joints.
7. Check alignment, whether with a tape measure or at a professional and have the tires balanced again. Again, like the steering stabilizer I believe these things are more of a neutralizer than a contributor to Death Wobble. Also if you are going to be replacing ball joints and tie rods this is something I would wait until after parts replacement before paying for a professional alignment. You can easily do a driveway tape measure alignment for your test drives and then pay for a proper alignment when you are fairly certain you have replaced the proper parts.