This could be an airleak after the airflow meter, any ventilate dragged in here isn t seen by the ECU and fittingly not compensated for and can thin the engine out and can as well as allow the engine to rev up considering not desired causing rasping running. As its a mechanical aberration it tends not to approach upon the deformity fresh and you can sometimes hear a hissing noise considering the engine running.
Its in addition to worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will every repercussion in insufficient fuel beast delivered to the engine. Might afterward be worth cleaning out the idle keenness rule motor / valve as these acquire clogged up following carbon and some brake cleaner washed through helps release things off.
This could be a large vacuum leak ,with the MAF amalgamated it is only measuring the let breathe that is getting like the MAF, therefore if the intake manifold is sucking in let breathe the let breathe 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. taking into account carb cleaner spray spray can in the area of the hissing behind the engine processing and behind you listen the engine stall or rev complex there is the leak ,could be a bad vacuum hose bad gasket on the manifold.