Check the hose clips for tightness and inspect the trunking for any cracks or splits and with all the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best quirk to find a leak is to have the engine handing out and warm and subsequently spray lighter gas /propane or brake cleaner just about each joint in turn. If the engine rev s taking place 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 tiny more roughly the misfortune history. It currently has a master tech attributed idle expose direct valve and tps installed. without moving anything, the last (used) ecu and my original, would control in the car without this symptom.
considering I begin the car, the engine surges going on amid 1200 and 2000 rpm back up and forth. I misused the IAC and the TPS next no modify in symptoms. I have noticed that several Lexus SC's have this same issue. Prior to this I would have to adjust the idle promptness screw to humiliate the rpm and it would keep for a while. Now, the engine is constantly surging to the tapering off where I cannot drive it for bell of broken to the drive train. Any experienced solution?