I have a 94 VW Golf with 180 000 Klm my check engin light is on it comes on and off periodically normally goes out when hard exceleration but not always I have had it to the dealer and other shops I have had it scanned for codes nothing showed up they erased the engin light but it still comes on when the light is on it really lacks power but when it goes out the power is restored until it comes back on whats wrong with my car............. Help!!!