I did the propane test and it appears theres a leakage around the #3 cylinder (the one behind #1), either around the fuel injector or the manifold gasket itself.

The gaskets are new, and when I spray propane or carb cleaner I do see a change in engine speed. Thus, assuming there is a leakage, I need to retorque the manifold bolts. All of them were torqued up to 20 ft lbs, I got this from another member, but this MIGHT have been for the 450 iron block. DO I need to torque them to higher specs, i.e. 20 Nm?

Assuming one injector seal/insulator leaks, would that really affect system vacuum that much?

Im hoping that is the case here, a retorquing of the manifold.

Vacuum gauage is SUPPOSED to stay pegged throughout the idle range, correct??