I've had this intermittent problem for about the last six months. Periodically, usually in stop-start city traffic, the engine starts making a loudish rhythmic clicking sound, accompanied by a significant loss of power. It speeds up when I accelerate, and causes my engine to die when I stop or slow down significantly. As long as I continue moving it tends not to kill the engine. When I restart, which usually takes a few attempts, it then holds idle fine and doesn't click anymore. It sounds a whole lot like a valve turning evil, except that it goes away just as suddenly as it comes. This happens maybe twice a week, sometimes more, sometimes less. Maybe this is just coincidence, but it seems to happen much more frequently on hot days than cold ones.

Any thoughts, things to investigate, remedies?

Thanks guys!