Clogged intake

[rapidride3]

Hello I decided to switch out from a 2 barrel intake&carb to a edel. performer and a edel. quadrajet on my stock 350. My center port between the intake runners (heat riser port???) was completely clogged on both sides of the intake manifold. What function does this port serve??? Does it have anything to do with the egr valve??? Why would it have clogged?? And would this affect any bad idle characteristics i was having?? Thanks,,, Matt