Vanguard,

Mine acted as you described. Almost like it needed to run for a while before it would run without dying. What I thought was it being cold natured was actuallt some kind of trash that was in the carb and broke loose, causing it to die. The trash looked like it had been there since it was manufactured. Inlet screen was clean, and I use a filter in-line, and a Walbro filtered clunk in my fuel jug. My needle setting are close to yours, low end just a tad leaner, I fly at sea-level. Cleaned it w/ carb spray and a little compressed air and have not had any troubles since.

Good luck,
Jon