I'll see what I can do about posting videos... looks like I can't post directly...
Idle vac when hot is steady 20". No apparent vac leaks and I have a gauge in the cab to watch it while driving.
Not using any oil now that I have the PCV sorted.
So curious! Frustrating, but I'm still having fun.
GM crate motor with 17,000 miles so I'm hoping it isn't something internal to the manifold!