This is getting interesting. This is a company truck. My boss had a similar incident, with this truck, where the truck entered his garage and ran over his tool box and pushed the tool box into and through the wall. He thought he was at fault and told me so. But, maybe not... And after discussing it with him, it's become clear that he probably experienced the same thing.
1) I left foot brake while racing. It's an effective tool and results in faster lap times.
2) I used my (very capable) left foot because I was in line for quite some time, so it was a "share the load" situation.
3) Additional brake pressure "solved" the problem, but the engine was straining mightily against the brakes, and in fact, did very slightly spin (lets call it rotate, as it was not a burnout) the right rear tire. I could clearly hear the brakes groaning at first.
4) The floor mat is not an issue in any way. It's anchored down and is only on the flat floor. Not near the accelerator.
5) I mentioned that I looked at the pedal when this was happening. NOTHING WAS ON THE PEDAL, and it was not depressed or stuck in any way.
6) Apparently, this is not the first time this has happened to this truck.
7) There have been other reports of similar behavior from this model truck. One where the truck accelerated beyond the speed limit, 3 times, by itself, on a rural road.
8) Shutting the truck off and re-starting solved the problem for him, and for me.