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Just to 'throw-it-out there, have you checked (both members) for an air leak in any of the vacuum lines? Along those lines, does engine vacuum enter into the passenger compartment in dash area (HVAC or any valves inside dash)? IF SO, maybe a short burst of starter fluid or carb cleaner (along with listening for engine RPM increases) might help Must mention, be aware of sparks present where you are spraying (which is why only SHORT bursts of spray).
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