Also check for vacuum in the line going to the bov. The previous owner of my GST used a plastic vacuum T which broke apart and blocked the "port" inside the intake manifold. I verified the blockage by attempting to push air into the "port" with an air compressor. Solved my problem by dislodging the plastic fitting with a metal coat hanger.
Apologize to 'eclipsetech' for using/modifying his engine photo. The red highlight is the line I'm talking about. Sorry for the confusion with the term "port".
