Hello, I have repaired on top of 30000 vehicles in my career and I compulsion to ask you questions since I am not there in person to gather facts, data, or to test your vehicle. I may ask you to con psychiatry in my stead. If study is needed and you would rather not exploit testing, I can present my best advice, Fuel pressure?
Its plus worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a below par pump will every result in insufficient fuel creature delivered to the engine. Might plus be worth cleaning out the idle promptness govern motor / valve as these acquire clogged up later than carbon and some brake cleaner washed through helps free things off.
taking into consideration I start the car, the engine surges happening amongst 1200 and 2000 rpm support and forth. I changed the IAC and the TPS in imitation of no change in symptoms. I have noticed that several Lexus SC's have this similar issue. Prior to this I would have to familiarize the idle quickness screw to humiliate the rpm and it would hold for a while. Now, the engine is continually surging to the narrowing where I cannot steer it for siren of damage to the steer train. Any experienced solution?