WJs have more bump steer than death wobble but crappy out of balance tires will shake any front end.
The 42RE in the 99 to 04 WJs is actually pretty good. There is a problem with a pressure transducer setting a fault code but that is easily replaced once the pan is off.
The 4.7L has a bad history of failed valve guides and burned valve seats, blown head gaskets, warped heads, and blown radiators. The 4.7HO version is slightly more reliable but I have done a ton of work on them too.
Matt is right about the rest of the vehicle falling apart. Broken door wiring, blend door problems on the ATC models, leaking heater cores, t-case problems, the aluminum rear diff bearings going out and lockers making noise, front diff bearings, CV boots constantly tearing, front diff axle seal leaks, transmissions blowing up due to improperly installed primary filters and blown out side plates on the valve bodies. Add to that bad window regulators, crappy power seat adjusters, a/c line leaks, sun roof tracks breaking, and door panels that never stay secure.
Honestly, I'm not sure if there is anything on a WJ that I haven't fixed, removed, or replaced. I bought a brand new fully loaded 2001 Limited many years ago, ex wife had nothing but problems with it and she wound up selling it after dumping a couple grand into it.
IF I ever bought another one, without a doubt it would be an 04, 4.0l, 42re, select trac t-case, manual HVAC and cloth interior w/o power.