This could be an airleak after the airflow meter, any freshen dragged in here isn t seen by the ECU and so not compensated for and can lean the engine out and can as a consequence permit the engine to rev taking place subsequent to not desired causing rough running. As its a mechanical irregularity it tends not to aim upon the anomaly spacious and you can sometimes hear a hissing noise in the manner of 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 ill pump will all outcome in insufficient fuel being delivered to the engine. Might in addition to be worth cleaning out the idle speed manage motor / valve as these get clogged going on bearing in mind 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 going on 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 occurring and is warmed up? oftentimes in engine feint many factors may cause the thesame symptom(s)