I just did some reading and watched a video diagnosing bad u-joints. It is likely that one of them may be bad. I’ll do my best to check tomorrow when I go back to fill up the differential. Would a bad u-joint cause apparent loss of power symptom I described though?
As for expensive paper weights - yeah, this thought has crossed my mind as well. I’d like to figure out what this issue is first, then see about selling it. Mostly I hate that I get 18 mpg, and I don’t really need an SUV. I haven’t had any issues getting parts yet, but I can see how that could be a problem.