Just happened again after accelerating away from a stoplight. This time I shut it down before it got above redline so no physical damage done. The over-rev happens at random and without apparent cause. There is no time to react other than kill the ignition. By the time the engine is restarted it's back to normal.

This is hard to explain, but the engine doesn't feel 'right' for a few seconds seconds after recovery. It's like there is a slight miss but then all is fine.

I am wondering if perhaps a sensor is messing up. Is it theoretically possible for a malfunctioning (e.g.) tps to direct ecu to send enough fuel to rev out the engine? Or, must the throttle plate be physically open for sufficient air to enter the intake? I'm thinking the throttle plate must be open but on the other hand with the clutch in, a super-rich condition might be tolerable.