I'm reposting this issue here, as I believe that this is a common problem that others like me are belly aching over.

Transmission problem - at 45k miles the check engine light came on and I noticed that the car jerked when put into drive and also jerked when it shifted from 1st to 2nd. also, I believe the overdrive wasn't working.
Anyway, Dealer said the tranny speed sensor needed to be replaced ($280 incl. labor).

My problems have been pretty consistent with the attached link:
http://autos.msn.com/research/vip/R...id=3179&src=vip

Hope this helps. My jeep is becoming a real headache.