mine was running on 3 cyinders but that was caus it was running on water!! due 2 my head gasket goin tits up
but before i knew it was running on water it was killing plugs once a week, they were jet black when i removed them ( this is only cylinder 3 ) so it MITE be head gasket but dont quote me on that. could be ur metering head tho.

sorry this hasnt realy helped lol