[Hozer 88GTConv]

With all ports plugged (PCV and the other two tree ports underneath the intake) and the TB opening duct taped!
I got 3-4" Hg, that is the needle was whipping between 3 and 4 inches at about 250 cranking rpm.

Hmm, should it have been a steady reading? If it is just leaking at number 5, will that cause it to fluctuate on the gauge?

BTW, thanks in advance for the input (esp PKRWUD). I have been working on this problem for over a year. I have taken the heads off twice, rebuilt them and r and r'd the intake manifold half a dozen times with Fel-pro 1250's and 1262's.