My fiancee has a 2000 mountaoneer and she is very happy with it. Problems so far were the typical Ford ball joints, fuel pump and fuel pressure regulator. She is approaching 80,000 miles. The 5.0 gets about the same mileage as the 4.0 explorer and has alot more power for towing and other things.
I almost forgot, this has the dreaded 4r70w tranny. If there are no records, change the fluid as soon as you get it, and use MerconV instead of the Mercon that the maual calls for. These trannys are great if taken care of, but they don't like neglect. The other good thing is that Ford placed a drain plug in the torque converter on this year (and a few other years) so you can get about 95% of the fluid out by yourself without paying for a flush. If you want a link to directions for a fluid chnage on this tranny, let me know.
Good luck
