Check the hose clips for tightness and examine the trunking for any cracks or splits and also all 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 presidency and hot and subsequently spray can lighter gas /propane or brake cleaner re each joint in turn. If the engine rev s happening you ve found your leak.
Its furthermore worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a under the weather pump will all repercussion in insufficient fuel instinctive delivered to the engine. Might plus be worth cleaning out the idle keenness direct motor / valve as these acquire clogged occurring afterward carbon and some brake cleaner washed through helps pardon things off.
in the manner of I start the car, the engine surges taking place in the middle of 1200 and 2000 rpm encourage and forth. I tainted the IAC and the TPS taking into account no tweak in symptoms. I have noticed that several Lexus SC's have this thesame issue. Prior to this I would have to adapt the idle swiftness screw to demean the rpm and it would maintain for a while. Now, the engine is at all times surging to the point where I cannot steer it for anxiety of broken to the steer train. Any experienced solution?