Check the hose clips for tightness and inspect the trunking for any cracks or splits and moreover every the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best way to locate a leak is to have the engine organization and hot and next vaporizer lighter gas /propane or brake cleaner roughly each joint in turn. If the engine rev s going on you ve found your leak.
Its after that worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all consequences in insufficient fuel being delivered to the engine. Might in addition to be worth cleaning out the idle eagerness direct motor / valve as these get clogged occurring with carbon and some brake cleaner washed through helps free things off.
with I begin the car, the engine surges in the works in the middle of 1200 and 2000 rpm back up and forth. I tainted the IAC and the TPS taking into consideration no amend 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 subjugate the rpm and it would keep for a while. Now, the engine is permanently surging to the dwindling where I cannot steer it for apprehension of damage to the drive train. Any experienced solution?