Dom
what are you using to seal the ends of the intake to the block? Are you just using silicone or are you using the gasket that is supplied with the intake gaskets for the end rail. I had a problem with those gaskets holding the intake up too high and the intake gaskets would not seal properly. I left out those end gaskets on each end and just used silicone on the ends and then the intake gaskets sealed up on the ports with no leaks.
Just a thought