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Ok - let’s assume you are indeed referring to the brake booster ..
Vacuum booster can easily be eliminated as the culprit concerning the idle issue by simply disconnecting the vacuum supply hose then plugging the hose with a suitable device so no vacuum will be drawn in - - does engine now idle normally ?
▪️This is for TESTING purposes ONLY while vehicle is parked!
▪️DO NOT DRIVE VEHICLE WITH VACUUM HOSE DISCONNECTED FROM BRAKE BOOSTER !!
Good luck!
Ok - let’s assume you are indeed referring to the brake booster .. Vacuum booster can easily be eliminated as the culprit concerning the idle issue by simply disconnecting the vacuum supply hose then plugging the hose with a suitable device so no vacuum will be drawn in - - does engine now idle normally ? ▪️This is for TESTING purposes ONLY while vehicle is parked! ▪️DO NOT DRIVE VEHICLE WITH VACUUM HOSE DISCONNECTED FROM BRAKE BOOSTER !! Good luck!