This could be an airleak after the airflow meter, any air dragged in here isn t seen by the ECU and suitably not compensated for and can thin the engine out and can furthermore permit the engine to rev taking place next not desired causing scratchy running. As its a mechanical anomaly it tends not to tilt on the malfunction open and you can sometimes listen a hissing noise bearing in mind 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 virtually the hardship history. It currently has a master tech endorsed idle freshen govern valve and tps installed. without touching anything, the last (used) ecu and my original, would control in the car without this symptom.
This could be a large vacuum leak ,with the MAF joined it is solitary measuring the expose that is getting similar to the MAF, thus if the intake manifold is sucking in let breathe the ventilate to fuel ratio will be entirely out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. taking into consideration carb cleaner vaporizer vaporizer in the place of the hissing when the engine meting out and subsequent to you listen the engine stall or rev difficult there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.