RX7Club.com - Mazda RX7 Forum - Help! Idle issues

Hey all,

I need help troubleshooting an idle problem. here is the deal.. the ride idles at or about 750-720 rpms with accessories off. when they are on it idles about 820 rpms. But the problem is that the car feels like its missing real bad. Basicly when its idling there is periods of heavy studder and idle drops to about 400-500 then comes back up to 800 then studders some more. The symptons gave gradually been getting ever so worse, so i changed the plugs ( 300 miles ago ). After the change i only got a little bit of studder that you could barely feel and it didnt effect the tach at all. However this morning on my way to work i stopped at a light and it felt like the engine was searching for an idle point ( bouncing from 500 to 1000 rpms. Now the car accelerates fine and still has power and i pull anywhere from 15.5 to 16.3 lbs of vaccum. Any and all help would be greatly appreciated. im trying to stay away from the dealership!