I wasn't going to install UCAs with the new shocks. And my plan was to only set the front 5100s at the .85 setting. It seems that those who have claimed that an upgraded suspension fixed the issue are the ones that did a more extensive and larger lift(new shocks, coils, UCAs, etc). So now that my problem is back after the new wheels and tires, I am not sure what I am going to do(I do know that I can't afford a $3k suspension overhaul right now).
There is a long thread about this issue on CarGurus here:
Toyota 4Runner Questions - What will cause a steering wheel shimmy at 60-65mph other than tires, ... - CarGurus
Maybe some people from here are the same ones that have posted there. Regardless, if you go all the way down and look at the last posts made by "Levi", he claims that the "driver's side CV cup" is the culprit and that a bushing solved his problem. I don't recall this ever being talking about on this site. Pumacat, do you know if the dealer or the regional tech looked into this when they had your truck for a month? Maybe someone with more mechanical knowledge could chime in but I know that a larger lift will change the angle of the CV axle. So maybe that new angle of the CV after a lift caused it re-position and "tighten" up, hence fixing the vibration that they previously experienced. Is this even a plausible thought?