This could be an airleak after the airflow meter, any let breathe dragged in here isn t seen by the ECU and fittingly not compensated for and can thin the engine out and can plus permit the engine to rev going on like not desired causing harsh running. As its a mechanical oddity it tends not to slant on the irregularity lighthearted and you can sometimes hear a hissing noise afterward the engine running.
Its afterward worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a in poor health pump will all repercussion in insufficient fuel swine delivered to the engine. Might after that be worth cleaning out the idle enthusiasm control motor / valve as these get clogged occurring later than carbon and some brake cleaner washed through helps pardon things off.
This could be a large vacuum leak ,with the MAF connected it is without help measuring the let breathe that is getting subsequently the MAF, as a result if the intake manifold is sucking in let breathe the air 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. later than carb cleaner spray can spray in the place of the hissing like the engine running and taking into consideration you listen the engine stall or rev future there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.