This could be an airleak after the airflow meter, any air dragged in here isn t seen by the ECU and therefore not compensated for and can thin the engine out and can then allow the engine to rev taking place with not desired causing harsh running. As its a mechanical deformity it tends not to turn on the deviation light and you can sometimes hear a hissing noise later than the engine running.
Might next be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can realize a quick irregularity locate if you unplug the meter and rule the engine without it. if the engine condition is the similar next chances are the meter or the link to it is faulty. Its with worth cleaning the MAF sensor wires, as they can acquire coated in imitation of dirt on top of mature which after that offsets the reading. Use some admission cleaner or brake cleaner to spray onto the wires to cut off the dirt on no account be next to the wires similar to anything as they are no question fragile
This could be a large vacuum leak ,with the MAF united it is lonely measuring the freshen that is getting later than the MAF, fittingly if the intake manifold is sucking in air the ventilate to fuel ratio will be categorically out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. similar to carb cleaner spray can spray can in the place of the hissing gone the engine organization and like you hear the engine stall or rev well along there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.