'97 Volvo 850GLT with about 130K: I'm living with the beast howling every now and then like a mistreated camel. No matter how I beat on the car, it just keeps on ticking; so I'd like to put an end to the embarrassement. It sounds like it's coming from the turbo, goes on and off with the gas pedal, and then finally stops, comes on again after a longer stop. Turbo waste gate??