Hello, I have repaired beyond 30000 vehicles in my career and I need to question you questions back I am not there in person to collect facts, data, or to exam your vehicle. I may ask you to show investigation in my stead. If psychoanalysis is needed and you would rather not sham testing, I can have enough money my best advice, Fuel pressure?
Its moreover worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a in poor health pump will all result in insufficient fuel monster delivered to the engine. Might along with be worth cleaning out the idle promptness govern motor / valve as these get clogged going on in the manner of carbon and some brake cleaner washed through helps pardon things off.
bearing in mind I start the car, the engine surges in the works in the company of 1200 and 2000 rpm back up and forth. I distorted the IAC and the TPS next no change in symptoms. I have noticed that several Lexus SC's have this same issue. Prior to this I would have to accustom yourself the idle zeal screw to humiliate the rpm and it would withhold for a while. Now, the engine is permanently surging to the lessening where I cannot drive it for dread of damage to the drive train. Any experienced solution?