This could be an airleak after the airflow meter, any air dragged in here isn t seen by the ECU and in view of that not compensated for and can lean the engine out and can next allow the engine to rev in the works like not desired causing rasping running. As its a mechanical irregularity it tends not to slope upon the defect open and you can sometimes hear a hissing noise next 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 sick pump will every upshot in insufficient fuel instinctive delivered to the engine. Might as well as be worth cleaning out the idle zeal rule motor / valve as these acquire clogged happening next carbon and some brake cleaner washed through helps release things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you up to date on every maintenance; spark plugs fuel filter pcv vlave etc? have you performed a visual inspection and listened to engine as it warms in the works and is warmed up? oftentimes in engine affect many factors may cause the thesame symptom(s)