i'm thinking this is nothing to do with the engine, i think it could possibly be a wiring fault if one of the injector wires randomly shorts against a earth the injector will hold open this will fill you bore up in seconds with fuel then as the piston comes up the pressure of the fuel siting on the piston blow the head gasket on the water way or worse breaks the block.

this happened to me!! i had a fucked l8 which was filling pot 3 with fuel the car will still drive at the point it causes a missfire its too late the gaskets gone! i blew a 4layer wrc gasket.