The only high rpm I've seen from a bad 02 sensor is the breif sruge in idle speed, just after it almost dies in that 20-30 second, cycle.

Again, I found that if I turn it off, then re-start, it get's it set straight. If it happened more often, I'd go to the JY and get another IAC.

I wonder if anyone has pulled their IAC, and seen the motor move the pintal. Pretty sure there is no relay...(or the latch relay?). Anyway the point was, the ECU mainly deals with mil/amps except for the injectors. (I think). The IAC motor deals with some real current. One way an ECU might fail is a transistor for an injector. Anyway, just rambling. If the power to run that IAC motor goes through the ECU, there might be more to look at. Just trying another IAC is a thought.