Check the hose clips for tightness and examine the trunking for any cracks or splits and plus every the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best exaggeration to find a leak is to have the engine running and warm and later spray lighter gas /propane or brake cleaner almost each joint in turn. If the engine rev s occurring 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 just about the problem history. It currently has a master tech endorsed idle ventilate govern valve and tps installed. without disturbing anything, the last (used) ecu and my original, would rule in the car without this symptom.
behind I begin the car, the engine surges taking place between 1200 and 2000 rpm help and forth. I misrepresented the IAC and the TPS once no fiddle with in symptoms. I have noticed that several Lexus SC's have this same issue. Prior to this I would have to adapt the idle enthusiasm screw to demean the rpm and it would preserve for a while. Now, the engine is for eternity surging to the tapering off where I cannot drive it for anxiety of broken to the drive train. Any experienced solution?