[xj31]

first thing i would do is check all the fuses.the re trans actually has an electronic governor as opposed to the hydraulic governor on a rh.Th rest of the trans is pretty much the same.Anyways,your jeep has a seperate trans controller or tcm.You can get codes out of it if you have a scanner.The diagnostic connector for the tcm is inside the jeep under/behind the ashtray.Most of the problems I have seen have been simple like a blown fuse,so check those first.I have seen a few controllers fail also,but it could also be a problem in the trans.
also are you sure its a 42re?That would be with a 4.0 liter.A 5.2 has a 46rh and those had problems with governors sticking.That causes the exact problem you describe