Actually the IAC (Idle Air Control) valve does not work like an EGR valve but maybe you mean it has a pintle to block off the air passage kinda like an EGR valve blocks the exg gas passage until it opens. But they are two completely different systems. The IAC is normally a stepper motor but on this vehicle it should be an electronic throttle body that dont have an IAC motor as it has a motor to control the throttle blade position to control all throttle positions. But on vehicle with the IAC I have found that most of the time if you have an idle flucuating because the IAC valve is moving around its not because the IAC valve is bad because its actually working since it moves and changes the idle speed. The problem usually is something is telling the IAC to move and then the PCM is working it. Most of the time when I would get an erratic idle it was a bad TPS as the TPS volts would not stay steady at idle and when ever the TPS volts moves off idle the PCM will open the IAC some to hold the rpm up a little when you let off the gas and then bring it back to normal idle to help keep it from stalling. Basically the electronic throttle body can do the same but it controls idle by the throttle blade position. I dont see that problem as much under light throttle but it can happen. But as said your best bet is have the codes checked and also have it scanned to see just what is going on when it happens. Otherwise you will just be guessing. Even an EGR valve opening way to soon can cause that problem along with other things. Ron