Rough Riding???

My car is running extremely rough like its in 2nd gear. I don't think its anything to do with the transmission, because when you watch the engine idling its running ruff, I did have the engine overhauled year half ago, I just replaced the plugs and carb. I currently have the electronic ignition but haven't put it in yet. I am wonder what can be causing it??? Do you think once i throw the new distributor in, it will correct itself?? or is it the card needs to be professionally set??