An old coworker did this to himself in his OBS F250. Packed new bearings, threw the hubs together and bolted them on till they were tight and called it good. Soon after he starts getting some steering wander and then death wobble and was chasing suspension and steering parts trying to fix it. A few weeks after doing the hubs, one of his front bearing came apart during one death wobble episode and took out his spindle. The other hub was also extremely loose. Turns out he didn't know you're supposed to spin the hub as you tighten the spindle nut, so once he drove on it the preload loosened up and everything went downhill from there.

 

Upper ball joints should be snugged down tighter than spec if running over-sized tires.
One other thought here is to adjust your Toe-in 1/8-inch more than your current setting and give it a run-for-the-money. Wide rubber likes to wander.
You might add one more steering stabilizer and see if that helps any.

Now, on my '77 F350 longbed Crew Cab, i had converted from 2wd to 4wd running '76 F250 front leaf springs.
I hit a badger hole buzzing up the interstate and experienced very embarassing Death Wobble. Hmm.
What cured my issue was to install a panhard rod from a full-sized '76 Bronco, and my death wobbles went away.
The front axle is a '79 F350 Dana kingpin 60 with a steering stabilizer. The kingpin D60 has spring loaded upper ball joint nylon bushings, non-adjustable.

Keep wracking your brain, and if you wind up in a straight jacket, we will know why.

For everything you've done, I am amazed to hear you are encountering Death wobble

 

If it's a bad tire, that wobble can overcome any and all brand new parts.
My second experience with it gave me a chance to experiment. In this case with my Bronco, I had an idea of what it might be (a bad front tire), but changed out all the wear items anyway. Just as an experiment because I was not convinced that loose parts alone would cause it. I'd experienced plenty of worn out suspension and steering parts over the years without any of them leading to a Death Wobble.

So on went new trackbar bushings, radius arm bushings, offset polyurethane C-bushings, new ball-joints, new tie-rod and draglink, adjusted toe-in multiple times in both directions and even went to the extent of buying a brand new steering box from Ford (it was not a bad deal at only $175 at the time). None made any difference.
The gearbox was the last item on my list due to cost and me thinking my old one was still in pretty good shape (it wasn't). I was pretty sure it was a tire, but I replaced every one of those other parts individually and then re-tested for wobble each time.
I could repeat it each and every time out on my local boulevard because it had a small bump in just the right spot for me to hit. I'd try at different speeds from 30 to 45 mph and got the same result.

Finally, before I did any further damage and buggered any of my new parts with the serious shaking, I rotated the tires front to back and that fixed the whole thing 100%.
I was not too bitter about spending the money because each of those items replaced was at least slightly worn anyway. At about 80k miles (if I remember) even the manual steering box was showing some age. I didn't know that until I put the new one on though!
That new one made the whole driving experience so much better!

So even though plenty of others have had a loose, worn or broken part fix their wobble, for me it was a tire.
Luckily only one in my case, so I did not have to replace it. Just kept it on the rear until they finally wore out.

Paul

 

That would sure do it too!

Friend of mine had Pep Boys repack his wheel bearings before a trip. Apparently they didn’t have the right spindle socket so just “adjusted“ the bearings with hammer and screwdriver. 🙄
Never got a death wobble out of it, but the smell of burning grease and melting bearings got him over to the side of the road before losing a wheel!

 

I know you said new shocks but pull them and run them thru a full stroke a few times.
As said straight axles like in a 68 Dodge van I drove in high school would get DW on the high way after hitting a bump.
Found 1 of the shocks was dead and the front wheel would bounce up & down till you slowed to 5 MPH, not good when the speed limit was 65 MPH at the time!
Dave ----