2000 Boxter S Problem on cold startup

[sdwagner]

I am a new Porsche owner. I have a 2000 boxster S with 16k miles. For the past week when I go to start my boxster. The engine feels like it is missing a cylindar, the car makes a noise kind of like a misfire and has a rough idle, for about 30 secs and sluggish at first and then it levels out. The car is fine for the rest on the day, it starts just fine until I let it sit overnight and start it again the next day. I have no check engine light on.

Any adivse would be helpful! Thanks