Been a while since I've been around the site, but thought i should add to this thread.
I had a similar problem with my 2000 tundra.
Pulled up to a stop sign and stopped.
The throttle jumped up and the truck started moving out into the intersection.
I literally STOOD on the brakes to try to hold the truck in place.
It jumped a couple times, moving the truck out far enough that after the throttle backed off on its own after a few seconds, I had to back up to get the front bumper out of the crossing lane. It never happened again after that, but considered selling it off. I never did hear back from the NTSB after I reported it, probably because I was not the original owner, though it was a Toyota Certified vehicle, complete with an aftermarket bumper.

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5.7L RC Longbox, 4X4 SR5