Im also interested to know what codes you get. My car has the exact same problem you have described. The only code it ever throws is Misfire Cyl 3, i have swapped coils and plugs, all with the same result. Even replaced plugs and coils over the summer, still same problem when it gets below 40 degrees.
One odd thing i have found, is when it starts running ruff and i clear the code, it immediately runs smooth?