Idle air controlled by the base setting of the throttle body and the idle air control valve? ECM uses information from various inputs, such as coolant temperature, manifold vacuum etc. for the effective control of the idle speed? Cleaning may help?:
It should close virtually fully. When I mean fully, it should very nearly seal the throttle body, but *** never closes at 90 degrees across the direction of flow. If you can see light past it, or know it is open slightly, either it is malfunctioning or the throttle needs reset. I cannot remember the proceedure, but it'll try find the proceedure for you.
Throttle reset .... ignition on for 90 secs, then off for 90 secs, then start and idle for a few mins. Don't touch the throttle pedal while doing this. You might need to try this couple of times.
You have a fly-by-wire throttle on the V6, so when cleaning don't force the butterfly open by hand, it can damage the electronics and drive gear. I always strip my throttle body down to clean it even on my old TS with throttle cable. That way the actuators don't get moved out of sync.