what type of choke are you running?
it may need adjusting a little.

and you may need to check the fuel pump to make sure it is pushing the right pressure. I think a stock pump puts out around 10 psi. but that is not all you should look at. disconnect the line to the carb and have it pump some fuel into a jug that you can see the flow of fuel comeing out. if its not a good steady flow than you may have a bad pump or a restricted fuel line.

try this and let me know what it's doing.