Edelbrock has a great tune up chart on their site to calibrate their carbs! Is it an electric choke or manual choke? Possible the choke is not going fully open when it warms up, floats set too high, too much fuel pressure (Edelbrock carbs don't like much more then 4-5 psi), or just plain too rich in the intermediate circuit. Their tuning guide should help you sort out the problem.