Death wobble is a common demon on Jeeps with 33" and larger tires running on the highway. While it can be a real bear to solve, it almost always involves some combination of caster and/or toe in out of spec plus one or more worn components in the front end, either tie rod ends, drag link ends, pitman arm, ball joints or panhard bar. One of the biggest causes is the panhard bar mount being loose, or having worn ends allowing the differential to oscilate side to side on up and down suspension motion. I understand that the panhard bar is not a possibility here on a MII IFS - just pointing out that it is a common demon on 4WD's.
The steering dampner by itself is not going to solve death wobble - it is indeed an important component, especially with big, aggressive off-road tires, but if you have things out of spec the steering dampner is a temporary band-aid at best. IMO you need to be looking for a worn front end component, plus being sure your caster and toe are set on the money.