This could be an airleak after the airflow meter, any expose dragged in here isn t seen by the ECU and appropriately not compensated for and can lean the engine out and can plus permit the engine to rev in the works in the manner of not desired causing harsh running. As its a mechanical idiosyncrasy it tends not to face on the malformation buoyant and you can sometimes listen a hissing noise next the engine running.
Thanks for your response. I just checked what you mentioned, that I hadn't already checked, except fuel pressure.Let me say you a tiny more roughly the trouble history. It currently has a master tech attributed idle let breathe rule valve and tps installed. without heartwarming anything, the last (used) ecu and my original, would govern in the car without this symptom.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you happening 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 taking place and is warmed up? oftentimes in engine measure many factors may cause the same symptom(s)