Check the hose clips for tightness and examine the trunking for any cracks or splits and along with every the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best mannerism to locate a leak is to have the engine admin and hot and subsequently vaporizer lighter gas /propane or brake cleaner with reference to each joint in turn. If the engine rev s taking place you ve found your leak.
Its in addition to 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 all repercussion in insufficient fuel creature delivered to the engine. Might then be worth cleaning out the idle eagerness govern motor / valve as these acquire clogged happening later carbon and some brake cleaner washed through helps free things off.
in the manner of I begin the car, the engine surges taking place amid 1200 and 2000 rpm put up to and forth. I tainted the IAC and the TPS next no amend in symptoms. I have noticed that several Lexus SC's have this same issue. Prior to this I would have to adjust the idle speed screw to demean the rpm and it would preserve for a while. Now, the engine is all the time surging to the point where I cannot steer it for fright of broken to the steer train. Any experienced solution?