Jeep Repair: A few problems, constant velocity, input shaft

Question
Hi, I have a couple couple questions concerning my 1999 Sahara. First, when I'm doing 10mph or under i get a strange banging from something rotating, it seems to be coming up from the transmission but I'm not sure(could it be the input shaft?). Also when I reach highway speeds of about 60mph it vibrates violently and they can be felt through the transmission, steering wheel, and seat(hopefully the two are related). Finally the once in awhile(more often on long highway trips) the "check engine" lamp comes on and the jeep spuratically hesitates or jerks varying in intensity. When I use the onboard diagnostic test (holding in the odometer trip, and turning the key to on) it does not show any error codes that should be displayed. Any help is appreciated.

Thanks,
Cam

Answer
Have you checked the u joints?  I think this model could have a constant velocity u joint, they can go bad and be hard to diagnose.  That is the only thing I could think of for the vibration and cluck.  The check engine light sounds like you may have a miss in the engine, the only way to figure out what the engine light is to check it with a scan tool, you can buy cheap scan tool for about 90.00.  Hope I could help you and God Bless!