OK, OK ... I was just kiddin'
OP, I've had my XJ for 19 1/2 years. I've put over 150,000 miles on it, and have had three experiences with death wobble.
First, how are your tires? All 3 time's I've experienced death wobble, my tires were at the end of their life.
Second, how do you maintain your tires and alignment? At 5,000 miles, I went to my local Firestone store and put lifetime alignment on my Jeep, and lifetime rotation and balance on the tires. I've done that with every set of tires since.
After that, every 5,000 miles, I've gone on the Firestone website and downloaded a 19.95 oil change coupon, and got my oil changed, tires rotated and balanced, and front end aligned. I strongly recommend that. Not only does it keep my XJ riding good, it gets longer wear out of the tires, and helps with death wobble, as you'll see later.
HINT: Tip the guy who does the work 5 bucks. Once you've done that a few times, and the word gets around, the most senior (and experienced) techs will insist on getting to work on your rig, and they'll do an extra-good job for you. More than once, they've caught small problems and fixed them for me for free.
I had my first date with DW right at 40,000 miles. I'd never heard of it before, and it scared the crap out of me. The tires were shot, so I put a set of 255/70 15 Bridgestone Dueller AT Revos on it, and a factory replacement steering stabilizer.
I didn't see even a hint of death wobble again for 55,000 miles.
Right at 95,000 miles, I started to feel just a bit of pre-DW when I'd hit certain bumps on the highway during my daily commute. Always the same bumps. The tires were 50,000 mile warrantied, and had 55,000 miles on them, but instead of replacing them, I had them balanced and rotated again, and the DW went away.
3,000 miles later, I started seeing pre-DW again, but a balance and rotation resolved it again.
3,000 miles later, same story.
I'd found a set of 16" Moab wheels, and ordered tires for it. While I waited for them to come in, I had to take a trip to St Louis (400 miles away). As soon as I left there for home, the death wobble started. It was unbelievably bad at 50-60, but once I got over 60, it was OK. It would take 4-5 tries to get past 60. It got worse and worse until I drove the last 50 miles on surface streets, and couldn't go above 35 mph. The last 10 miles, it shook like crazy, no matter what speed I drove at.
By that time, I'd done a ton of research on DW, and knew a heavy duty steering stabilizer was the answer ...
OK, OK, I couldn't help myself.
I ended up buying a Death Wobble Kit from Kevin's Offroad. It consisted of an upgraded adjustable trackbar with Rockwell 75d durometer bushings and a super-HD steering damper. I installed it, and mounted 245/70 16 Duellers on the Rubicon Moab wheels and had 40,000 miles completely free of DW.
Right before I was due for my 140,000 mile balance, rotation, and alignment, I began to feel a little pre-DW. Just like with the last set of tires, the rotation, balance and alignment resolved most of it.
Right before 145,000 miles ... same story.
Looking under the Jeep, we checked the steering stabilizer and found it was worn out. I got the idea of finding the heaviest-duty, most badass stock-replacement steering stabilizer known to man, and posted a thread on here asking which one that might be.
What followed was something like the Running of The Bulls, except all of the bulls were rabid, and I was dressed all in red. It was epic. Imagine Bernie Sanders showing up at a TEA Party rally.
"STEERING DAMPERS DO NOT FIX DEATH WOBBLE!!!"
Anyway, before the mods deleted the thread, one guy made what I thought was an ingenious suggestion. He said, instead of spending a ton of money on a bulletproof steering damper, I should go buy a Monroe stock-replacement steering damper for 29.95, because it has a lifetime warranty! If it goes bad in 10,000 miles, you just take it back and get a new one.
I thought that was brilliant, and headed down to Auto Zone. At the last minute, I couldn't help myself, and bought the Monroe Super Badass Heavy Duty one for 69.95, but it has a lifetime warranty, too.
No more death wobble.
at 151,000 miles, the steering suddenly became very loose. We found out the steering box was bad, so we replaced it. While we were turning the wheel and watching the box work, we noticed the KOR Death Wobble Kit track bar was flexing all over the place. We pulled it off and found the bushings had failed so badly we couldn't get them, or the bolt out.
We switched it out for a Rugged Ridge track bar.
http://www.ruggedridge.com/hd-adj-front-track-bar-18205-05.html#product_tabs_additional_tabbed
Death Wobble is gone completely. The only problem I had was, when I'd go over a sharp bump, even at slow speed, there would be a huge WHAM! sound. It reminded me of the sound of my ex-wife slamming the door after she found the strip club charges on my credit card statement.
Turns out, the mounting bracket is MUCH more substantial than the stock one, or the KOR DW Kit one, and it was interfering with the spring perch. A little bit of grinding, and it was fine.
So, what I think my long story offers you is a clinic on basic DW.
As tires wear out, you'll tend to get DW.
Unbalanced tires and/or alignment out of whack affect DW.
Track bar affects DW.
And last, and certainly most controversially, replacing the steering damper ameliorates DW. It may not resolve the root cause of it, but in my mind, if I can put a 70.00 steering stabilizer with a lifetime warranty on my Jeep and get 10-15,000 DW-free miles ... that's a win.
Especially when all I have to do when the DW starts again is pull the steering damper off, go down to Auto Zone, and get a new one .. for FREE.
By all mean, check the things mentioned above carefully, but if you just start throwing parts at death wobble, you're going to have a very sore wallet ... and you might still have DW.