I'm no fan of the 4.0, no fan of the AW4........that said-
Our XJ will pull 3-4K uphill with no problem. Braking is another matter. Over 250K miles.
See link below-
I've gone through my engine harness, eliminated the C101, improved my grounds, replaced all sensors.....etc........
Last weekend I replaced my fuse block, all new connectors. Truck had not been started in over a week, turned key and to my surprise it fired up immediately. What the fuse block has to do directly with the ignition circuit...IDK, however, with every improvement I've made to the electrical system the engine runs better, starts faster.
I read all the complaints regarding lacking of power, and the standard answer is- throw a stroker at it.
If you have a problem, it's mechanical or electrical.
See his experience-