On my 96 the forward O2 sensor went bad. It caused the engine to buck and lose power intermitently. The trans would down shift due to the engine running bad and losing vacumm. Check the codes. If it is an O2 sensor, I suggest replacing both. At least mine had 2, one on down pipe and one after the cat.
2000 XJ Limited, 4.5 Rusty's All spring lift; 265/75/16 BFG KM2's; 4.0, aw4, 242.
2001 XJ Sport, 4.5 Rusty's lift, 32x1150x15 Hankook Dynapro MT's. 4.0, aw4, 231, 8.25 rear with power trax locker.
08 f 150 2.5 lift, 33's, arb.