Didn't do this today but thought it was time to report the issue and apparent fix.

My car (2004 Coupe with 80,000 miles) was getting a bit rough at idle some times, stumbling from time to time when I'd pull up to a light. It would also hesitate sometimes when I tipped into the throttle. Finally threw a CEL and the code showed P0121 - throttle position sensor. I did some quick research and this site came up - P0121 - OBD-II Trouble Code

So, I took their advice and picked up some throttle body cleaner and MAF cleaner and had at it. Yep, the throttle body was really dirty but cleaned up quickly and easily. It's been almost a week and not a hint of stumble at idle. Total cost: about $8. Total time: about 30 minutes.