engine missfires, runs ruff

Miss fires, black smoke from tail pipe, and all the spark plugs on the passenger side look like the bottom of an old engine, full of black oil i guess. when I kick down on the excellerator the black smoke is so thick that it left black sut on the garage door. the code says random missfire. but I am confused as to why all the spark plugs on the passenger side are fouled but the drivers side are fine.