I've had a few intake manifold gasket leaks in my 1997 F-150 4.6l with an all-aluminum intake manifold over the years, and have changed the gasket a couple of times, but now it seems there's a leak at the air/fuel port going into cylinder 6 causing coolant to foul the number 7 spark plug, bringing up code P0307. How is this possible? I ran the engine until hot and turned it off and observed water/coolant seeping from the air/fuel port gasket where the manifold attaches to the head just at this port. I cannot see any coolant/water running down from number 5 near where the water port and thermostat is located. There was no other indication of coolant/water in plugs 5 or 6. Anyone have any ideas as to what is occurring?

 

Your head gasket is bad/worn and need to replace it.