Runs rough first few minutes

[Rc 415]

Hey guys, I am having some trouble with my 83 stepside running rough for the first few minutes after starting it up, and I need some help. Ok, first off this only happens if I havent started the truck for a day or so. So when I start the truck after its been sitting, it expells a fair ammount of black smoke out of the tailpipes for a few minutes, and its kinda jumpy as if its about to die or somthing. then after the black smoke stops, there is a gray smoke that dissapates very quickly that comes out the tailpipes for a few minutes until the truck warms up, I think thats normal though. There was one day that I hadnt started the truck for 2 days, and when I did start it it was very rough and a lot of black smoke and it died shortly after starting, but I was able to start it back up without any problems and it did the black smoke for a few more minutes and then it got better like always. I am thinking that this involves the carberautor and or choke, can anyone give me any help on what I should do to fix the problem?