help needed auto box fault

97 xj has 2 faults, first is idleing at 1500 rpm and the second is auto box, started of woundnt change up untill 4000rpm now seems to be ok changing when it should but cant get 4th or o/d.
have done the key switch and hold the trip/reset button which returned a code of 45, i have searched the net to find that code could be a number of things, Anybody have any ideas?

A bad TPS sensor would cause the idling and shifting problem. It's pretty common.