Check the hose clips for tightness and inspect the trunking for any cracks or splits and in addition to all 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 running and warm and after that spray lighter gas /propane or brake cleaner approaching each joint in turn. If the engine rev s up you ve found your leak.
Thanks for your response. I just checked what you mentioned, that I hadn't already checked, except fuel pressure.Let me tell you a little more roughly the burden history. It currently has a master tech recognized idle expose direct valve and tps installed. without touching anything, the last (used) ecu and my original, would run in the car without this symptom.
in the manner of I start the car, the engine surges going on surrounded by 1200 and 2000 rpm put up to and forth. I changed the IAC and the TPS with no bend in symptoms. I have noticed that several Lexus SC's have this similar issue. Prior to this I would have to acclimatize the idle readiness screw to lower the rpm and it would preserve for a while. Now, the engine is every time surging to the narrowing where I cannot drive it for danger signal of damage to the steer train. Any experienced solution?