Steve, one last thing to check before pulling that manifold - oil pressure switch or oil pressure sender or line at the back of the manifold. The seal for the manifold should be under negative pressure if your PCV system is working well, but that oil fitting is under pressure and can pass a lot of oil right in the same place. I have made this assumption before, resealed the manifold, just to find it still leaking - tightened the fitting and the leak was gone...
