Ok today I was messing with the stang, and decided to pull the vacumm advance hose off the distributor, and my idle (which was really choppy) cleared up like no other. What gives?
The port that you pulled the hose off of, did it have vacuum at idle? Vacuum advance is only suppose to come in off idle (1200 or so I think). What type of carb is it? I know that on Edelbrocks there are two vacuum ports, one is for the vacuum advance, and the other is intake manifold vacuum I think. The manifold vacuum is there; even at idle, while the vacuum advance one is not. Your problem might be that you have the hose on the wrong port, and therefore are running your engine at idle with a very high advancement. See if you're getting vacuum at idle on the port you had it plugged into. It would also be a good idea to check your timing with timing light.