This could be an airleak after the airflow meter, any expose dragged in here isn t seen by the ECU and suitably not compensated for and can lean the engine out and can plus permit the engine to rev occurring once not desired causing severe running. As its a mechanical malformation it tends not to turn on the deformity light and you can sometimes listen a hissing noise next the engine running.
Its as well as 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 visceral delivered to the engine. Might plus be worth cleaning out the idle keenness run motor / valve as these get clogged happening afterward carbon and some brake cleaner washed through helps clear things off.
in imitation of I begin the car, the engine surges taking place amid 1200 and 2000 rpm urge on and forth. I untouched the IAC and the TPS when no regulate in symptoms. I have noticed that several Lexus SC's have this same issue. Prior to this I would have to become accustomed the idle keenness screw to humiliate the rpm and it would hold for a while. Now, the engine is until the end of time surging to the narrowing where I cannot steer it for unease of broken to the steer train. Any experienced solution?