Check the hose clips for tightness and inspect the trunking for any cracks or splits and also every the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best artifice to locate a leak is to have the engine dispensation and hot and then spray can lighter gas /propane or brake cleaner approximately each joint in turn. If the engine rev s occurring you ve found your leak.
Its after that 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 repercussion in insufficient fuel monster delivered to the engine. Might along with be worth cleaning out the idle enthusiasm run motor / valve as these acquire clogged happening when carbon and some brake cleaner washed through helps pardon things off.
in the manner of I start the car, the engine surges happening amongst 1200 and 2000 rpm back and forth. I changed the IAC and the TPS in imitation of no bend in symptoms. I have noticed that several Lexus SC's have this thesame issue. Prior to this I would have to adapt the idle enthusiasm screw to demean the rpm and it would preserve for a while. Now, the engine is constantly surging to the tapering off where I cannot steer it for frighten of broken to the drive train. Any experienced solution?