detroitxj

while driving on the highway for about 30-40 mins my xj will rev up too 3000rpm and it loses power i have to get on the gas more revving it 4-5000 to get it to pick up any more speed. it seems like it wont shift up or down but if i park for a little while it goes back to normal driving(5minutes is the shortest time i have had to wait while a couple hours was the longest) but it seems to do this sporatically as i have taken it to school several times but it has only done it once on that same route so far. also when i start it has a rough idle and once in awhile it will stall but starts right up again it only does this when engine is cold. Any ideas on why it loses power?

Coondawg_07

Have you checked your transmission fluid? Check for level and see if it smells burnt. Sounds to me like It may be slipping.

Killabrew

Check codes? I had a similar problem and it was upstream O2 sensor.