Not a cure but a possible work around. Prior to loading any car, test your pedals at the Calibration screen to verify the game sees them correctly. Which AJR, there are 4 engine choices.
edit: Just tried it with the Judd powered AJR, and yes, the rpms climb EVEN BEFORE the power is turned on. The rate of increase is measured, it is not like an engine in neutral was revved suddenly, more like an electric charge.(it takes a couple of seconds to climb to the max) The rpm rate just rises and pegs the needle without any input from the driver OR with any power switched on.
Moving the pedals does not affect the runaway engine, only pressing the A key to allow the AI to take the car out brings normal operation.