Dave,
Just grasping again but this thought occurred:
A. Started after the intake change-right?
B. Goo only in VC's-right?
Guessing that water is entraining into the
oil feed at the rocker pedestals in each head. That would contaminate only the valve cover area. Don't know where such water could come from and don't know why the goo doesn't go down the corner head drains and contaminate the valley/crankcase areas. You don't
oil through the pushrods right?
Just trying to get someone smarter than me to think away from all the gasket/head/porosity/testing stuff beat to death here. You've covered all that in my view.
If you haven't already-get KC to listen and offer a thought or two. I KNOW he's not responsible for this problem.
Getting a headache
.