la22bay

Anyone experiencing with a 1992 500SL 103k miles, automatic transmission, running great but now notice this sound like something is rubbing this vibration noise sounds like fan is touching or something, or rubbing sound coming from front passenger side, only happens when in reverse gear, Also I notice after running and return to park the idle is rising above 1000rpm, usually stays between 500/800rpm and when idle is revving high, hard thump when shifting into drive or reverse gears, MB Tech suggest MAS unit need to be replaced. Does this control idling?