Thermostat?
Thankfully, my car was under warrenty when it happened, so all they did was replace the faulty thermostat and that was it.
I had a similiar problem one time when I had my Eclipse. I would be stopped, have the car in neutral, and the RPMS would exceed 3,000. The problem was the thermostat, the car thought the engine was very cold, so inherently it gave it more gas to warm up.
Thankfully, my car was under warrenty when it happened, so all they did was replace the faulty thermostat and that was it.