Jeep engine races when in park

Thanks for your response! Yes, it does the same thing whether it's cold or has been driven for 20 minutes or so. My daughter was driving it home and had a flat, locked the keys in the car and the battery went dead (flashers and radio on) waiting for the courtesy patrol and a locksmith. They got it all fixed and jumped the jeep off and it was fine at that point. After driving for about 20 minutes to a service station is when it first happened. Now it does it every time we put it in park. Your question made me wonder if it was just happening in park and it appears that it's happening in every gear except drive. When we start it, the engine is revved up through every gear until we hit drive and then it jerks and slows down. My daughter also stated that it felt "jerky" while she was driving it If you have any thoughts, I would really appreciate it. Finding an honest mechanic around here is a bit difficult and it would help to know what I needed to have repaired.

Thanks!