That's like saying "Do an engine swap to fix your oil leak problem."
Mine doesn't run rough in the cold weather, although it does run rich while warming up. Rough idle points to other problems, not just the choke. Have you checked everything else out? Strong ignition? Vacuum leaks? Exhaust leaks? Valves adjusted properly? Dirty carb? etc?
These items can all contribute to rough idle. If it stops when it gets warmed up, thats a clue.