An accelerator pedal needs to be physically pushed down, there is no activator other than human force.
On a drive-by-wire system, if the signal is lost, it go' s into limp mode.
Can a false, or bad Throttle position Sensor give a bad signal to the ECU/PCU?
How about a bad cruise control module, or actuator?
A bad cable, or sticky throttle plate can create some problems, but you need a good TPS + Throttle plate control to get horse power.
It's probably a bad gremlin, or back seat driver.