Check the hose clips for tightness and inspect the trunking for any cracks or splits and along with all the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best mannerism to find a leak is to have the engine giving out and hot and later spray lighter gas /propane or brake cleaner vis--vis each joint in turn. If the engine rev s occurring you ve found your leak.
Its with worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a not a hundred percent pump will every consequences in insufficient fuel visceral delivered to the engine. Might also be worth cleaning out the idle quickness run motor / valve as these get clogged stirring past carbon and some brake cleaner washed through helps free things off.
following I begin the car, the engine surges going on amid 1200 and 2000 rpm incite and forth. I misrepresented the IAC and the TPS past no tweak in symptoms. I have noticed that several Lexus SC's have this similar issue. Prior to this I would have to become accustomed the idle speed screw to demean the rpm and it would retain for a while. Now, the engine is each time surging to the lessening where I cannot steer it for unease of broken to the steer train. Any experienced solution?