This could be an airleak after the airflow meter, any freshen dragged in here isn t seen by the ECU and therefore not compensated for and can thin the engine out and can plus permit the engine to rev up bearing in mind not desired causing rough running. As its a mechanical idiosyncrasy it tends not to point on the anomaly light and you can sometimes listen a hissing noise afterward 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 little more just about the difficulty history. It currently has a master tech certified idle expose control valve and tps installed. without heartwarming anything, the last (used) ecu and my original, would rule in the car without this symptom.
once I begin the car, the engine surges in the works with 1200 and 2000 rpm back up and forth. I untouched the IAC and the TPS as soon as no tweak in symptoms. I have noticed that several Lexus SC's have this similar issue. Prior to this I would have to adapt the idle swiftness screw to degrade the rpm and it would maintain for a while. Now, the engine is all the time surging to the narrowing where I cannot drive it for bell of damage to the drive train. Any experienced solution?