Intake manifold torque

Thanks to everyone for their input. But just to clarify a few things.
1. Engine is still on the stand.... Has never even had the carb mounted yet.
2. Gaskets were in a engine tech kit. But seemed to be a good quality.
3. I torqued per 2000 FSM which is in steps, but 72in lbs, then 12 ft lbs.

Not sure why, setting on a stand they seem to have loosened, esp. the center bolts.
I ordered a felpro gasket set and a sealer "Gasgacinch" to use with the gasket.
This was reccommended by Mbaird.
Intake manifold gasket sealer?

Thanks again for everyones input.