Car Accelerates On Its Own problems of the 2003 Ford Ranger

2003 Ford Ranger sudden acceleration. While braking the vehicle suddenly accelerated. I was able to turn off the engine after the engine speed reached about 4,000 rpm. After shutting off the engine I checked to see if my floor mat was causing this problem, I removed it from the driver side and restarted the engine without touching any pedals. The engine started and revved up to 4. 000 rpm again. This is the 3rd time my Ranger did this. I took it to river view Ford in oswego, they checked it and said they could not replicate the problem. The second time this happened I nearly collided with the vehicle in front of me. I took it back to Ford for the same reason, and they told me the next time it happens drive it to the dealer, at 4,000 rpm. (I don't think so) there are no recalls for my vehicle as the dealer checked. What can I do?.

2003 Ford Ranger was purchased by the police deparment as a utility truck. On 2 separate occasions, with 2 different police officers driving the truck, the vehicle suddenly accelerated even thought both police officers report they had their foot off the accelerator and on the brake. The first incident occured 2/24/04 and the truck was taken to the dealer. They were unable to duplicate the problem but replaced the throttle body. The next incident occurred 3/11/04. Different police officer had multiple incidents where the truck surged foreward even though foot was off accelerator and on the brake. The vehicle was again taken to the local dealer and once again the mechanics were unable to duplicate the problem but did replace a valve assembly- throttle air bypass. The vehicle has 4000 miles on it.