How old is the battery? How badly corroded is the ground lug on the end of the battery ground cable? Have you seen any glowing of the "battery light"? What I am getting at is that this sounds like an electrical/electronic problem. SOMETHING caused the ECM to command the throttle body and injectors to do this. (If it was, say, just a throttle body sensor, the injectors would not have been commanded to provide enough fuel to do this, would it?) Why would the ECM do this?

Other than the battery and electrical issues - the pedal sensor would be my next guess. If the pedal sensor reported that you had your foot to the floor, with the front wheel sensors not indicating motion, the ECM limits engine speed to (I THOUGHT) 4200 or 4400 RPM.


EDIT: Here is a thought. My SECOND Crossfire (the Graphite one below in the photo) did something twice in 77000 miles that was similar to what you had happen. IN fact, it was the SAME THING. I'd left the car on Highway 180 in North Georgia and went for a 10 minute walk in the woods. I returned and started the car - and headed down hill - soon I realized it was accelerating -I pressed the clutch in and the engine went right to 4200 rpm or so. All I could do was turn the key off. I then turned it to "ON" and let the clutch out, it did it one more time going down hill - did not do it again until about three months later -when it did it at the EXACT same spot again!

Conditions: 85-90F, high humidity, less than 1/2 tank of gas, sat for maybe 10 minutes, went down hill upon startup, on a Saturday both times. I never saw it do it again, and I never figured out what it was that made it happen.