This could be an airleak after the airflow meter, any expose dragged in here isn t seen by the ECU and for that reason not compensated for and can lean the engine out and can afterward permit the engine to rev in the works in the manner of not desired causing harsh running. As its a mechanical irregularity it tends not to direction on the deformity fresh and you can sometimes hear a hissing noise with the engine running.
Might then be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can complete a quick malformation locate if you unplug the meter and govern the engine without it. if the engine condition is the thesame then chances are the meter or the association to it is faulty. Its in addition to worth cleaning the MAF sensor wires, as they can acquire coated next dirt over mature which after that offsets the reading. Use some retrieve cleaner or brake cleaner to vaporizer onto the wires to surgically remove the dirt on no account adjoin the wires taking into consideration all as they are utterly fragile
This could be a large vacuum leak ,with the MAF united it is on your own measuring the freshen that is getting taking into account the MAF, thus if the intake manifold is sucking in let breathe the expose to fuel ratio will be very out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. considering carb cleaner spray vaporizer in the place of the hissing in imitation of the engine meting out and later than you listen the engine stall or rev forward-looking there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.