Engine has a massive vacuum leak, and I believe its this POS valve do-hickey. Not 100% on its working dynamics but I assume a leak anywhere in this is not good. Literally a 3/4" feed between the air cleaner base and the intake manifold with this valve in the middle controlled by a 25" spike of manifold vacuum . Strange thing is that it is fairly new (installed 5 years ago and under 1000 miles on it, but it was old stock, 1976! Vacuum diaphragm is 44 years new.
