This could be an airleak after the airflow meter, any ventilate dragged in here isn t seen by the ECU and hence not compensated for and can lean the engine out and can after that permit the engine to rev happening in imitation of not desired causing gruff running. As its a mechanical irregularity it tends not to slant on the defect lively and you can sometimes hear a hissing noise bearing in mind the engine running.
Might moreover be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can get a fast malfunction find if you unplug the meter and rule the engine without it. if the engine condition is the same then chances are the meter or the relationship to it is faulty. Its after that worth cleaning the MAF sensor wires, as they can get coated behind dirt higher than era which subsequently offsets the reading. Use some door cleaner or brake cleaner to spray onto the wires to cut off the dirt upon no account be next to the wires like anything as they are extremely fragile
This could be a large vacuum leak ,with the MAF related it is single-handedly measuring the ventilate that is getting in imitation of the MAF, in view of that if the intake manifold is sucking in let breathe the let breathe to fuel ratio will be utterly 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 in the area of the hissing once the engine paperwork and with you listen the engine stall or rev complex there is the leak ,could be a bad vacuum hose bad gasket on the manifold.