Need Help!

[84TonkaToy]

Hello,

I have a 1984 GMC and just recently its started having what i think is carb problems. it has a edelbrock performer intake manifold and a basic edelbrock carb. It starts up and runs great but when i drive it and i come to a stop at a light the thing will die everytime. i then have to punch the gas down and keep trying to turn it over. when it starts again it has a lot of trouble staying running for 5 to 10 min then its fine. i have had the carb rebuilt and tuned and looked over front to back and no one can seem to figure out whats wrong. any idea would be awesome!