Hey guys, just wondering if anyone can help or has experienced something similar.

About 6 months ago, my Golf started to idle roughly, blowing black smoke and emitting a strong exhaust type smell from under the hood which would also enter the cabin. It was using 3L/H at idle too. I took it to the dealers and they replaced the Airflow meter. This fixed the problem and the car ran better than it has in ages. Until 2 weeks ago, when it started to show exactly the same symptoms again. Just wondering if it's possible the new airflow meter could already have died or if it may be something else like the O2 sensors? Is there any way I can test the airflow meter without the use of VAGCOM?