This could be an airleak after the airflow meter, any freshen dragged in here isn t seen by the ECU and correspondingly not compensated for and can lean the engine out and can along with permit the engine to rev taking place next not desired causing gruff running. As its a mechanical malformation it tends not to slant on the deviation lighthearted and you can sometimes hear a hissing noise subsequently the engine running.
Its after that worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a ill pump will all repercussion in insufficient fuel mammal delivered to the engine. Might then be worth cleaning out the idle promptness rule motor / valve as these acquire clogged occurring later carbon and some brake cleaner washed through helps pardon things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you occurring to date on all maintenance; spark plugs fuel filter pcv vlave etc? have you performed a visual inspection and listened to engine as it warms stirring and is warmed up? oftentimes in engine action many factors may cause the similar symptom(s)