TNT last night

the pv is part of the power enrichment system. when there is vacuum above the pv# it stays closed, when the vacuum falls under that pv# it opens and adds fuel(power enrichment). the vacuum signal falls when the throttle blades open then the pv opens to keep the motor from going lean. when you are cruising you have a good vacuum signal and are just using the main jets which is good for fuel economy but not for all out hp which is why there is a power enrichment circuit. so all that crap being said a blocked pv is going to lean your motor out at a low vacuum signal or full throttle. which is why you need to add jet.