My engine on my 4 cyl. '05 Accord has been shaking recently too. I remember being at idle a few months back and the engine just started to shake eratically and it sounded as if a bucket of bolts were being shaked. I drive very conservatively and usually shift under 2000 rpm. (automatic tranny). I thought it may have been some bad gas (I use mid-grade). A few weeks after the incident I took the car to the dealer for something and also had them investigate the situation. They told me my fuel regulator chip was on recall so they replaced it. My engine still shakes a little more and is louder at idle although it still idles at normal rpm...I can sometimes even feel it shaking at higher speed. The engine never acted like this...any suggestions at to what it could be?

P.S. Its an '05 4cyl. automatic Accord sedan, with 27,XXX mi.