This could be an airleak after the airflow meter, any freshen dragged in here isn t seen by the ECU and for that reason not compensated for and can thin the engine out and can moreover permit the engine to rev occurring following not desired causing sharp running. As its a mechanical anomaly it tends not to direction upon the oddity lively and you can sometimes hear a hissing noise subsequently the engine running.
Thanks for your response. I just checked what you mentioned, that I hadn't already checked, except fuel pressure.Let me tell you a little more very nearly the suffering history. It currently has a master tech qualified idle air direct valve and tps installed. without disturbing anything, the last (used) ecu and my original, would run 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 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 pretense many factors may cause the thesame symptom(s)