i have an audi a4 2001 model 1.8L non turbo. It recently had a problem in idling(it was going up & down between 200 & 1000 revs whilst it was in park). i had it checked by the mechanic & he checked & cleaned the throttle body & airflow sensor (air filter & plugs were changed). after that the idling problem was solved the vehilce now has a high consumption on fuel (10L for 43km). what might be the problem?