I'd guess cruise control as well, since the throttle is drive-by-wire and there are TWO sensors for the pedal position, and if they don't agree, the engine goes into REP (Reduced Engine Power) mode. A single broken or shorted wire around the pedal can't cause unintended WOT behavior. But a CC issue or a PCM intermittent failure (very rare) might do it. Don't think I've read even ONE other report in ten years.
Definitely write it up as an NHTSA report so they can add yours to the list if it's happening to other owners with any frequency.
Rear fuse HVAC1 sends power to the CC on/off switch, but if you pull that you'll lose some other HVAC functionality. You should do that right away or yank the connector off the CC stalk to make sure that's not the source of the problem. And make sure any driver knows how to turn off the engine and overpower it with brakes, and has the strength to steer it without power steering in case of another incident. And inspect under the dash where the pedal position sensors are - make sure there isn't damaged wiring or a dangling sensor assembly.
