Heres the story. I suffer from the tank like idle as do many other Altima owners. So I decide to adjust the idle using the IACV. Now if I open the valve to idle at about 1000 rpm's the car is smooth as butter, only one downside, the car lacks noticible power. Close the valve, idles rough but the power returns. Can someone please tell me how the IACV actually works, as in what is going on inside? Why would there be a decrese in performance? Any other way to smooth out the idle. Oh and she idles at the appropriate 700 rpms, with no adjustments.