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 next allow the engine to rev happening taking into account not desired causing rasping running. As its a mechanical irregularity it tends not to tilt upon the aberration roomy and you can sometimes listen a hissing noise once 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 poorly pump will all outcome in insufficient fuel beast delivered to the engine. Might after that be worth cleaning out the idle speed govern motor / valve as these get clogged happening when carbon and some brake cleaner washed through helps free things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you up to date upon 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 accomplish many factors may cause the thesame symptom(s)