It might get dirty and then the hot wire resistance no longer properly equates to the air flow into the throttle body.
It might be damaged by vibration, or its connections may have developed poor contact, causes a change in resistance that also presents as a miscalculation in airflow.


I would try a MAF spray cleaner first to see if things improve.
Unplugging and re-plugging associated plugs also wipes their contacts clean (not talking about the wire connection here!).


Can always buy a new sensor if the DIY approach is no good.


The diode is probably a zener diode which act as a voltage regulator for the sensor wire.