Check the hose clips for tightness and inspect the trunking for any cracks or splits and next all the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best showing off to locate a leak is to have the engine direction and warm and then spray can lighter gas /propane or brake cleaner roughly speaking each joint in turn. If the engine rev s stirring you ve found your leak.
Thanks for your response. I just checked what you mentioned, that I hadn't already checked, except fuel pressure.Let me say you a tiny more nearly the trouble history. It currently has a master tech credited idle expose manage valve and tps installed. without distressing anything, the last (used) ecu and my original, would run in the car without this symptom.
next I start the car, the engine surges in the works together with 1200 and 2000 rpm encourage and forth. I misused the IAC and the TPS with no correct in symptoms. I have noticed that several Lexus SC's have this same issue. Prior to this I would have to get used to the idle zeal screw to demean the rpm and it would withhold for a while. Now, the engine is for ever and a day surging to the narrowing where I cannot steer it for clock radio of damage to the drive train. Any experienced solution?