It's a 1985 2.6 / Truck started smoking rely bad all of the sudden. I don't think it's the head gasket. at least there is no water in oil or bubbles in radiator when cold. Valve seals replaced a year ago and they look to be in place still. The number 1 plug fouls within a few minutes after running. Could this be caused by the jet valve? Is there a way to test? It looks like there threaded into the head. Can I just remove the valves and put plugs in? Thanks for the help.