Recently, my '95 MX6 LS (v6) has started idling rough at the start. The car starts fine and runs fine for the most part. When I first start the car it idles around 500 rpm (very low!?) and the lights are dim. If I rev the engine, the lights get brighter. While I drive, as long as I am on the accelerator, it runs fine. When I come to a traffic light or stop sign, it will idle back down around 500 rpms. It has done this several times but stalled only once at the light. If I am about to shut off my car in my driveway or a parking lot, most times it will stall. What gives?