Crankcase pressure; oil pool in valve cover

[john]

I would guess your compression is a larger factor in only being able to run 18psi but... I would guess the oil pool has to do with a crack in the valve cover. If you tighten it too much, it will crack very easliy. The spec is only about 3/ft#s. Check the oil cap gasket again and make sure it is rubber instead of plastic. That is all I can think of now.