check to make sure your tb butterfly isn't closing all the way. should have about 1/8" gap (may have to play with the adjustment to find what the car likes, trial and error)
I believe my throttle body butterfly is completely closed. I was under the assumption this was normal and the idle is completely regulated by the IAC valve. You're saying I should adjust the idle screw until there is a bit of a gap (1/8th inch)? I have no idea what the previous owners have done to the car, but you're saying if the butterfly is completely closed it will force the ECU to run in a "high idle mode" to compensate for the closed butterfly? This might make some sense because again, with the IAC valve disconnected the car revs and idles normally.
Is there any documentation available on adjusting the TB butterfly?
Also, if an injector o-ring was leaking, wouldn't there be a hint of gas smell in the engine compartment. I have not detected the faintest hint of a gas smell while working on the engine.