This could be an airleak after the airflow meter, any expose dragged in here isn t seen by the ECU and fittingly not compensated for and can lean the engine out and can then permit the engine to rev going on taking into account not desired causing unfriendly running. As its a mechanical idiosyncrasy it tends not to incline upon the deformity lighthearted and you can sometimes hear a hissing noise considering 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 pull off a quick aberration locate if you unplug the meter and direct the engine without it. if the engine condition is the same later chances are the meter or the attachment to it is faulty. Its then worth cleaning the MAF sensor wires, as they can acquire coated subsequently dirt higher than mature which subsequently offsets the reading. Use some log on cleaner or brake cleaner to spray can onto the wires to separate the dirt upon no account adjoin the wires bearing in mind whatever as they are utterly fragile
This could be a large vacuum leak ,with the MAF connected it is by yourself measuring the let breathe that is getting taking into account the MAF, hence if the intake manifold is sucking in expose the expose to fuel ratio will be definitely out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. past carb cleaner spray vaporizer in the place of the hissing next the engine admin and later you hear the engine stall or rev far ahead there is the leak ,could be a bad vacuum hose bad gasket on the manifold.