[Roadsters] won't stay running

[Tim]

70 1600 with new needle valves, empty floats and good level of gas in the float chambers. Car had been running great all summer except in the 105 degress we experienced last June and even then was still ok. Car has always been difficult to start when cold (air or engine), today was especially difficult at approx 45 degrees.  Once car is warm it will idle ok but when trying to drive it starts to sputter and won't stay running. 

I have carbs coming but wanted to take her out one more time this coming weekend for the Looong Race. 

Help. 

Thanks

tim