Check the hose clips for tightness and examine the trunking for any cracks or splits and plus every the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best way to find a leak is to have the engine management and warm and next spray can lighter gas /propane or brake cleaner not far off from each joint in turn. If the engine rev s up you ve found your leak.
Might afterward be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick irregularity find if you unplug the meter and manage the engine without it. if the engine condition is the similar next chances are the meter or the relationship to it is faulty. Its with worth cleaning the MAF sensor wires, as they can get coated past dirt exceeding epoch which after that offsets the reading. Use some right to use cleaner or brake cleaner to spray can onto the wires to cut off the dirt upon no account be adjacent to the wires once all as they are unconditionally fragile
when I begin the car, the engine surges stirring in the company of 1200 and 2000 rpm help and forth. I misrepresented the IAC and the TPS afterward no correct 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 quickness screw to humiliate the rpm and it would maintain for a while. Now, the engine is each time surging to the tapering off where I cannot drive it for alarm bell of damage to the steer train. Any experienced solution?