I have a 2003 Camry that has recently begun having issues. While driving or idle, the RPM's start going up and the temp guage immediately goes down to past the Cool. If I put it in Neutral the RPM's go higher and my engine is revving. If I were to take my foot off the brake, the car would go by itself. Eventually, the temp guage goes back to normal and my RPM's subside. However, if the car is in Park and this happens and I try to put it in drive, then I'm unable to start my car for about 15-30 minutes. I've taken it to the mechanic twice, and both times, they claim to "fix it." Can someone PLEASE help me? thanks.