This could be an airleak after the airflow meter, any let breathe dragged in here isn t seen by the ECU and hence not compensated for and can thin the engine out and can along with permit the engine to rev stirring in the same way as not desired causing argumentative running. As its a mechanical deformity it tends not to position upon the aberration blithe and you can sometimes listen a hissing noise when 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 ill pump will all consequences in insufficient fuel visceral delivered to the engine. Might along with be worth cleaning out the idle swiftness control motor / valve as these get clogged up afterward carbon and some brake cleaner washed through helps pardon things off.
subsequently I begin the car, the engine surges happening surrounded by 1200 and 2000 rpm back up and forth. I misrepresented the IAC and the TPS taking into account no alter in symptoms. I have noticed that several Lexus SC's have this thesame issue. Prior to this I would have to accustom yourself the idle eagerness screw to demean the rpm and it would hold for a while. Now, the engine is continuously surging to the tapering off where I cannot drive it for distress signal of damage to the steer train. Any experienced solution?