iscv? idle speed control valve? did you take your TB off or mess with any of your cables recently?
http://www.cygnusx1.net/Supra/Librar...ction=FI&P=106
in my experience, the only time I had high idle was when I took my throttle cable off and when re attached, it slipped and got snagged in a funky way. If you didn't remove any cables or adjusted them. recheck for leaks then diagnose your isc. yes on intake leaks also.. check around your accordion hose for unmetered air being sucked in. also on your intake plenum and lower manifold.