I have tried pulling the plug wires and it seems that #2 cylinder doesn't make much difference whether it is connected or not. But once again, that's at home after most of the symptoms have settled down. Another argument for roadside diagnosis as the problem is occurring. I had the intake and exhaust manifolds off yesterday while checking out the manifold heat valve/vapor lock situation and noticed signs of gasoline leaking down the sides of the block below the intake manifold ports. Also, bubbles showed up near the middle intake port with the engine idling after reinstallation. Do I need an additional sealant besides the metal foil-like gasket? How does a vacuum leak contribute to this problem? I come back to this manifold heat valve thing because the shop manual says that the excessive lean mixture caused by the heat valve stuck in the "on" position can cause sticking valves. I should add that for the most part the engine runs at the 180 degrees called for by the thermostat.

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