Engine cutting out at idle
 

I had my car (Audi A3 3.2 2004) start cutting out at the lights randomly one day home from work. Car stalled, I restarted it then the car stalled again, restarted again and held the revs above 2000rpm to stop it stalling.

Took it to the mechanic and they said the mass air flow meter was faulty, they replaced it at a cost of $NZ450.

Car ran fine for 2 weeks then started having exactly the same issue occuring. Took it back and they plugged in their diagnostic tool and said the car was running rich. Left it with them and they said the throttle body was dirty. Was charged another $190.

My question is if they found the mass air flow sensor to be faulty then why would the exact same issue occur 2 weeks later? If the throttle body was dirty in the first instance then why did they not check it if they were replacing the mass air flow sensor? And the second time it happened the air mass flow sensor I would assume would be working fine as they just replaced it, which would indicate in the first instance the mass air flow meter was fine the whole time, and that only the throttle body needed cleaning?

I need some thoughts on this.