Is it starving for fuel or running too rich? The black smoke means a richer fuel/air ratio. What's happening is when you step on it, the carb is dumping more fuel to make more power. That's a Performer series Edelbrock, right? There's a piston built into it, a little pump really. When you stomp it, that pump shoots a little extra gas into the carb's bore to make up for the lag time between you stepping on it and the mixture getting richer via the jets. It's called the acceleration pump.
One of the linkages coming off the side connects to that pump. If you're looking at the carb with the hood open from the front of the truck, the pump is on the front driver's side of the carb. The linkage that connects to it can fit into one of three holes. By changing to a different hole, you alter the throw of that piston, which alters how much gas it pumps when you stomp it. I believe the factory sets it in the middle hole. This should all be covered in the carb manual as well.
Here's a link to the manual in PDF format:
http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf
Which port on the front of the carb is your vacuum advance connected to?
