Sounds like something [ecu?] is raising the engine speed. Normally, if the engine is cold, or the ac is on, the isc v opens, and the idle raises, to about 1000rpms. It does this by letting air past the tb, which allows the engine to breath more, raising rpms.
Only thing I can think of right now [it's 2:30 am
] is maybe the tb is opend a little? :shrug: maybe disconnect the cable and see what happens. :|