Ive become pretty good at figuring death wobble since I spent so much time tryin to figure out my issue.  The 1st thing to do is set your steering knuckle bearings(trunion bearings) preload.   

   

but seriously,  I agree,  I recently had trouble with DW and found that the one TG trunion (no i didnt buy it, it was free from a friend) bearing i had used in the top of my drivers side knuckle simply would NOT hold preload.  I'd set preload and within 40 miles of hwy driving the preload would disappear.  Obviously the inferior bearing just could NOT hold preload    I was actually surprised at this figuring "hey its a steel bearing"