If you are using the 4 "AA" battery holder as your receiver pack, that may have gone low on voltage and when that happens your throttle will go wide open. At that point you have no controll over the car. Plug it in and see how your steering is. If it's weak or not working at all, there's your problem. Install new batteries and see if the problem goes away. Are you running a failsafe? If not I would get one ASAP. It'll save you buggy and keep some green in your pocket.