Ah, I see in mails I read after sending below, you have a blowing inlet valve.
Depending on how open it sticks, it can have dramatic impact, as far more exhaust will get blown back into the intake tract - the burnt gas volume is several times the volume of the original charge ( hot gases expand directly proportional to temp in degrees absolute so if burnt gas temp is 800c, volume is (800+273)/293). This dead gas will then get sucked into other cylinders. I guess on a flat 6 you would probably end up with the whole bank continually re-using this burnt gas. I would expect the engine would idle fine, and would only start to show problems as you bring up the power. The most common way to get a stuck inlet valve is injested crud from unfiltered air. Usually ehaust valves stick cos of damage caused by weak mixture and/or burning oil Pete > If you have a weak fuel to one or two cylinders, you would probably > have blow-torched a piston - been there, done that with out of balance > su carbs on an old MG Midget, so I don't fancy your poor air to one cyl > theory, I think it sounds more like your original fuel pump/blockage > theory. >