Check the hose clips for tightness and inspect the trunking for any cracks or splits and in addition to all the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best mannerism to locate a leak is to have the engine processing and hot and after that spray can lighter gas /propane or brake cleaner just about each joint in turn. If the engine rev s going on you ve found your leak.
Its moreover worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all outcome in insufficient fuel being delivered to the engine. Might in addition to be worth cleaning out the idle enthusiasm manage motor / valve as these get clogged going on taking into account carbon and some brake cleaner washed through helps free things off.
subsequently I start the car, the engine surges occurring amid 1200 and 2000 rpm encourage and forth. I misused the IAC and the TPS behind no correct in symptoms. I have noticed that several Lexus SC's have this same issue. Prior to this I would have to adapt the idle swiftness screw to belittle the rpm and it would support for a while. Now, the engine is continually surging to the point where I cannot drive it for apprehension of broken to the drive train. Any experienced solution?