Intake Leak

I think your going to trace it back to bad machine work ,possible wrong angel cut some were another note are your intake bolts too long bottoming out giving the appearance of being tight with all that cutting on everything or the shoulder bottoming out on the bolts, just another thought. also check to see how tight the bolts are going through the intake manifold you may need to open them up some to let the intake move smoothly when torqued down and not bind .