You may need to lean out your low speed needle. How is it accelerating? The low speed needle should be about flush during break in but you should start leaning (turn the needle in) it in after that.

Another thing you may want to check is that your fuel system is airtight. It sounds like it may just be starting at first because there's still fuel in the line, but while running it can't suck up enough gas to keep the car running. Just a few things you may want to check out.