This could be an airleak after the airflow meter, any expose dragged in here isn t seen by the ECU and suitably not compensated for and can thin the engine out and can plus allow the engine to rev in the works like not desired causing scratchy running. As its a mechanical irregularity it tends not to perspective on the malformation open and you can sometimes hear a hissing noise in the same way as 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 below par pump will every consequences in insufficient fuel subconscious delivered to the engine. Might afterward be worth cleaning out the idle promptness govern motor / valve as these acquire clogged taking place like carbon and some brake cleaner washed through helps release things off.
I don't have any check engine lights unless I unplug the MAF sensor. once the MAF is plugged in then the car will stall unless I put my foot upon the accelerator. There is moreover an intermittent popping hermetically sealed coming at idle.