This could be an airleak after the airflow meter, any air dragged in here isn t seen by the ECU and correspondingly not compensated for and can lean the engine out and can in addition to permit the engine to rev stirring subsequently not desired causing severe running. As its a mechanical malfunction it tends not to direction upon the anomaly well-ventilated and you can sometimes listen a hissing noise as soon as the engine running.
Its next worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a not at your best pump will all outcome in insufficient fuel being delivered to the engine. Might furthermore be worth cleaning out the idle quickness rule motor / valve as these get clogged in the works following carbon and some brake cleaner washed through helps pardon things off.
past I begin the car, the engine surges going on together with 1200 and 2000 rpm urge on and forth. I misused the IAC and the TPS behind no amend in symptoms. I have noticed that several Lexus SC's have this similar issue. Prior to this I would have to adapt the idle speed screw to belittle the rpm and it would preserve for a while. Now, the engine is every time surging to the reduction where I cannot drive it for warning of broken to the steer train. Any experienced solution?