when you adjusted the idle did you disconnect the idle air control valve while doing this, it is a must when you mess with the screw. if it's really low then you may need a friend to give it a little gas to get it to where it needs to be. i had to help my brother do this a couple of weeks ago. warm it up, disconnect the iacv, adjust, plug back up, remove the backup fuse and see what happens. my si sometimes feels like it has a miss sometimes at idle etc and esp when i let off the gas. everything is as it should but i have not tuned my setup either.

your idle with the IACV unplugged should be 480 +/- 50 rpm so that should be where you need to set it when it's unplugged. plugged in after adjustment should be 680 +/- 50 rpm on a manual tranny. hope this helps a little. when you hit the brakes, use the a/c, or have headlights on etc there will always be an idle change but it should go right back to where it needs to be. sometimes mine idles at 900 rpm for a couple of seconds then drops at a red light.. all of these things are controlled by your electronic load detector which i doubt is bad it's just something honda's do and i have seen it for years. as long as the idle returns to where it should after a few seconds it should be ok i hope i was thorough enough for you.