Engine should die, right?

Change the intake gaskets & get the composition ones & use Permatex "high tack" the red stuff in a spray can & use a thick/wide carefully placed swath of clear silicone on the front/rear rails in place of the gaskets letting it sit up overnight as the supplied front/rear gaskets can be too thick but if a massive vac leak it'd have to be an intake/head interface gasket/alignment prob I'd think

The engine has never run correctly. We bought a rebuilt long block and have been trying to get it running. Here's what has been done so far.

1- Started with a new Edelbrock Performer manifold and 600 cfm carb.

2- Changed the carb to a new Edelbrock 650 cfm

3- Changed manifold to a new Weiand Action Plus

Intake gaskets are Fel-Pro composite with a light coating of RTV and RTV on the end rails. Throughout all of this all vacuum lines are disconnected and plugged. We've sprayed carb cleaner all over the carb and manifold while the engine is running after each change. There is no change in the idle so I can't see how it's pulling air from outside the engine.

I suspect an intake manifold to head mismatch but since we've tried 2 different brand new manifolds I'm beginning to think there is something wrong with one or both heads. There's nothing else it could be, is there?

Thanks,
Ken

Does it have an EGR valve or similar smog valve if so check it or plug the lines off and try running the engine