If I am not mistaken, idling will be not right., and when you downshift to stop at junction or traffic lights or just slowing down to a halt, the rpm dips very low and at times your engine might just stop, have to re-start .... happen to me once but not the sensor faulty, it was just not connected after i replace the ori air filter., guess the same goes if the sensor is faulty.
1 thin for sure ur check engine will light up.. when ur air flow sensor is faulty, your ECU could not measure the correct amount of air vs fuel therefore power and fuel consumption will be affected.