please i need some help

i have a 1990 burb. it is a 350 efi i just changed the fuel filter and cleaned out the throtle body with spray. the truck runs great when i am on the gas but when i am trying to creep through traffic it seems to go and then die off and then go and then die off. like i am getting on and off the gas. sometimes it seems to iideal a little low sometimes to. but then other times it sems to have no trouble. very confused? any help???

Check the egr for being carboned up, may not quite be seating.