ok i just did a mpfi swap and when i took out my old manifold i noticed that a vacuum line i think it is, its in the middle of the 4 runner or intake tubes. goes down underneath the manifold and attaches to the block i think im not sure.. well when i cut the side attatched to the manifold it was clogged with carbon. and the other end was almost fully clogged too. on the new manifold p6 i think it is, the line is the one that attaches in the middle of the two other vacume lines. my question is, since this got glogged before will it do it again? and what is it for ?

 

pretty sure its the pcv valve. vacuums shouldn't ever get clogged with carbon because no gases ever go through there, just air.