I have always noticed with my hondata s200b, when my car is started up cold it will idle fine but when I give it a slight quick throttle the idle will drop considerably, sometimes it can actually die out. Or when I give it a rev and let go the throttle the revs drop down to like 400-500 and then goes back up. Again this is only when the engine is completly cold, once it warms up it idles rock solid at what I have it adjusted for.