It only happens when it feels like to. The idle will drop from the usual 570 - 600 rpm to the 500 mark and sometimes even below(in between the first and second marks, I believe about 460 rpm or so....
I adviced the service person to check, and they told me it has be checked and just need to be tune a bit. But after I have the car serviced, the problem comes on couple days later.
P.S. With or Without A/C, it still will drop, just that with A/C on, the car will run like as if the engine will be choked to death.....(as if there's not enough power to light the ignitions, but in fact, I have the battery changed just last fall).
Any help appreciated......