general problems of the 2006 Dodge Stratus

Since 2006 my '06 Dodge Stratus has spontaneously accelerated approximately seven times, most recently in February 2010. Idling in a driveway or at an intersection, the engine will begin to race as if I had floored the gas pedal. Only by shifting into park and/or turning off the ignition am I able to prevent the car from accelerating into the intersection or a wall. The Dodge dealer who regularly serviced the vehicle said they could not diagnose the problem unless the car was hooked up to their equipment at the time of the next occurrence. Consequently, nothing has been done to fix this.