Hey Mark,
This sounds counter intuitive, and I sure can't disagree with anything anyone said. I also had "cold start rough idle", using the choke full out. It always started fine, but took time to level out. On a whim and a Triumph, I started starting without touching the choke. Now it fires up smooth and idles smooth. Of course, this noon, after a 30dF night that theory might fall apart.
standard disclaimer: "Your results may vary"
jh
