Fuel version is the one I remember hearing during broadcast from 1991.
Urban bashing legends you've mentioned are just few of several circulating, like letting his engine revs drop too low while he was waving to the crowd in celebration, thereby stalling the engine, which is plain stupid just as switch theory as the car can be push started at tens of times lower speeds (he'd just have to change to lower gear and start the engine with inertia he had)
Officially, it was a gearbox failure, which explains why previous theories fail.