i recently finished a manifold swap on my f22b1 to a ported f23 manifold and now have a nasty resination coming from inside the manifold. it goes away at part throttle and doesn't seem to effect drivability by much if any. we also noted that pumping the brakes (yes they are vacum assisted) that idle increases and the resonation mostly or completely goes away. we're pretty sure it has SOMETHING to do with vacum in the manifold. any ideas?