Car Throttle Sticking problems of the 2009 Toyota Tundra

My 2009 Toyota Tundra was repaired by Toyota this past Friday as a result of the throttle body sticking open. . Ie would stall. After repairs, the truck drove fine for 2 hrs approx. After stopping for supper (1hr) I started my truck again. . . This time the engine accelerated in park upto 5,000 + rpms for 10-15secs and then down to 500 rmps. . . Then repeated this over and over. I waited til the rpms dropped to 500 and placed truck in gear to try to get it home. The truck accelerated and took off on its own. . . Almost taking me through a red light. I was able to press hard enough on the brakes to stop in time. . . . Then it took off again for another block without me doing anything but riding the brakes. I turned into a randalls parking lot when rpms dropped to 500 again,. . . Dodging people who were walking into the grocery store. When it dropped again, I pulled into a parking space and put truck into park. This, all while the engine was consistently changing from 500rpms upto 5,000+ rpms with no interruption's called the dealership, still shaking, but only one person was still at the dealership. . . He advised since they were closed that another dealer was open later. So I had truck towed there. My original repair, they would not cover under warranty (13,000 miles on truck) because they said I had violated the warranty by installing a fuel saving device, which had damaged the throttle body. I paid them to replace the throttle body assembly. . . And then (approx. 3hrs later) the truck decided to drive itself,. . . And I feared I was going to hit someone, both cars and pedestrians. I never thought what I had read about would happen to me.