For a long time I had a problem where if I don't give it enough gas on the throttle from a complete stop and just let go of the throttle, sometimes the RPM would dip really low and the whole car would start shaking. Sometimes it would just shut the engine off (basically stall) and all the lights on the cluster would light up.
Ever since I had my IACV cleaned a couple of weeks ago, it hasn't happened since. You might want to check that. And I also have a hole in my flex pipe, which I'm guessing could mess with my idle a bit too.