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 showing off to find a leak is to have the engine handing out and warm and later spray lighter gas /propane or brake cleaner in the region of each joint in turn. If the engine rev s occurring you ve found your leak.
Its next 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 outcome in insufficient fuel bodily delivered to the engine. Might after that be worth cleaning out the idle rapidity run motor / valve as these get clogged happening with carbon and some brake cleaner washed through helps forgive things off.
once I begin the car, the engine surges occurring in the middle of 1200 and 2000 rpm support and forth. I tainted the IAC and the TPS subsequently no regulate in symptoms. I have noticed that several Lexus SC's have this similar issue. Prior to this I would have to acclimatize the idle quickness screw to degrade the rpm and it would hold for a while. Now, the engine is at all times surging to the narrowing where I cannot steer it for radio alarm of broken to the drive train. Any experienced solution?