windstar bob

1999 windstar sel 3.8 liter 82k miles. started throwing the vacuum leak code. and positive fuel trims i did the intake manifold bolts, intake gaskets, dpfe sensor, pvc valve, purge valve, canister vent valve, checked egr system, fuel tank pressure sensor, o2 sensors, and maf sensor. fuel pressure is 32# and smoke checked the engine for vacuum leaks... the purge valve makes noise and if i put my finger over the vent opening next to the gas cap, it gets quiet and you can feel the vacuum leak so i plugged it. Why is there free flowing vacuum leak there? I am running out of things to check/fix. the purge valve vibration thread does not say if it was ever fixed... any help would be appreciated. Thanks, bob