While returning from OurY in our 2000 xj with auto transmission, 242 transfer case, and 456 gears. We developed a bucking sensation while driving on flat ground while in overdrive. Downshifting to 3rd did not seem to help the problem on flat ground but did help when climbing hills, Vail, and Eisenhower. I was thinking the tourney converter might be slipping but not sure. Checked oil when I got home and seems fine smells a little warm but still red. Any help would be appreciated.