6sigma

I've got an infrequent CEL with code P0304, #4 misfire. Has happened 4 times in 9200 miles on my 2003. 4th time was today, so I thought I'd post my findings and see if you gurus had any ideas. Car is stock. The CEL happens in a consistent scenario so I can describe what happens. After the car is fully warmed up, I then park it for about 30 minutes. On restart, I've got 2 bars of temp and the engine idles poorly - a little rough and low, 500-600 RPM. Makes you think it might die (but it never has). I'll then drive it normally, but it feels sluggish, kind of non-responsive, like it's bogging somehow. Within a half mile, the CEL comes on. If I drive it more aggressively I get no CEL. I've done the MAP whack, and checked common things. Car runs like a scalded monkey, even after the CEL comes on and the sluggish feeling goes away in about a mile. I've been pulling the fuse to reset the CEL, seem to cause no harm. Dealer says not to worry about it (they've only seen it twice for the CEL). Any ideas? TIA