hey everyone, i jus recently melted a valve, and the plug too, in the sixth chamber, this is jue to the ignition timing im told? so ive ordered a apexi fc ecu so i can get it mapped and sorted out? so i replaced the valve , headgasket etc, went to start her up and its running very lumpy and the idling is unsteady??? what could the problem be?? any suggestions would be very greatful, cheers guys, oh yeah its an rb20det.