Idle Air Controll Solonoid/Valve hanging open, but I think you would have hanging idle issues as well if that were the case.
When an auto car is engauged into D, the computer sends a signal to the IAC to increase throttle for the intended load, as well as it does this when you kick the A/C on to keep RPM sound.
Here is a wild guess, but have you checked the charging and battery system because a bad diode in an alternator or a internally shorted battery can cause the computer to go nuts. When I do a battery or alternator at work, esp with new cars, sometimes I have to clear codes because the faulty alternator/battery caused the sensors to read poorly and the computer raised the amber flag on the dash.