[Hozer 88GTConv]

Sounds like you didn't get a good seal re-installing your upper manifold.
I am not familiar with the TF intake, but look for a vacuum source "t" fitting or tree with some prongs coming from under the plenum.
All you do is plug a rubber fitting attached to a hose with a vacuum gauge and look for something around 10-12 inches/Hg.
Vacuum depends on your cam, idle rpm, etc.
You can get a guage for $12-$15 complete with various fittings and a hose from Advance, Pep Boys, Napa, etc... They are handy to have around.

Take some PB with a fine spray tip extender and put some around the seal between your upper and lower.
I have heard of some guys putting clay around the perimeter of the seal between the intakes and quickly finding the source of a leak.
Good luck.