Car Throttle Stuck Problems of Ford F-250

I had just been jumped by aaa because my truck wasn't starting; the aaa agent also cleaned the battery terminals. I intended to have it towed to the Ford dealer because I didn't think it would start. Since the aaa agent was able to get to start, I decided to still take it to the dealer to find out why the battery was dead (given they had the car for a month and had put in a new battery and starter, among other repairs). Driving the 7 miles to the dealership the car seemed to be accelerating on its own, the entire way, I only stepped on the gas once; it was going 35 miles/hour by itself (per the speedometer). I didn't know why this was happening and when I tried to slow down using the brakes, the truck was very difficult to stop, such that I nearly rear-ended multiple cars. It was all I could do to push the brake down and twice huge amounts of smoke came from under the vehicle (probably the brakes were now overheating?). When I was 500 feet from the dealership I took a quick left turn and honestly could not stop the truck, I threw it into park and shut it off just in time to miss plowing into parked vehicles. Smoke billowed out from below the hood. I have never been so frightened in my life-I was sure I was either going to smash into someone since I couldn't stop or the truck was going to implode in fire, or something and I would be dead. I was not able to successfully stop it using the brakes. The parking brake was also not working (which is also why I was returning it to the dealer). When I asked the service person at the Ford dealership if he'd seen a stuck throttle like this before, he said, "yes, sometimes when vehicles sit for a while". This is a Saturday, so they are going to evaluate the problem on Monday. The service rep also said sometimes cleaning the terminals might contribute to extra conduction, which might have caused the acceleration issue.