When I turn on the jeep it idles fine. I can rev it up and its good. When I put it in drive it hesitates when you start to drive. It starts to do it when it passes 1000 rps. If it smooths out its fine until you have to slow down and when you accelerate it does it again. I had real big problems with this when I was in a higher elevation. But when i went to a lower elevation it wasn't as consent but it still occurs.