blow by?

my 318 has oil leaking around the oil fill cap. i replaced it with one that was vented because it was all the parts store had and it stopped the leak until the foam in it got soaked and now its dripping. there are no other leaks on this engine it runs flawlessly. i have removed the dip stick and the oil fill cap with the engine running and do not feel any kind of air coming out. the area where the oil cap goes on the valve cover doesnt look very flat but its kinda wrinkled like its been hit with a hammer. also did a tune up and all the plugs looked great. is this a blow by issue or maybe something else? the oil makes its way to the manifold and smells aweful