[Hozer 88GTConv]

I too have a lot of oil in my upper intake runners. In particular number 5. I think that my pcv letting way too much through and on my GT40 intake, the way the vacuum tree runs underneath the plenum it seems to be pulling in a lot in number 5. In fact , it may be the reason I am fouling number 5. It is wierd that it is bad in just one cylinder, but the vacuum tree position makes it look like something worth checking out.
After checking valve seals, compression, etc, it seems that the oil is too high in the runner (in the upper runner!) to be a problem in the head.
I run one moroso breather on the passenger side vc. I also have a Melling high-volume oil pump and my oil pressure is seldom below 60 psi. And yes, I gotta clean the area every month because of oil vapor.
I think you are on to something, and I have read that there is a particular motorcraft pcv that should alleviate the problem. I think that is what XLR8R was talking about.