I am no expert and not saying this will fix your problem by any means, but I would bump up the timing unless you are using a better octane gas than 92 or 93. I originally set my timing to what the book calls out and it was a no go as my engine ran crappy with the iron heads. Once I set the timing up to around 12 it ran a lot smoother and my vacuum wasn't going all over the place. I also moved dizzy vac source to manifold vac. You still might have a vac leak but this might help you idle and run smoother to figure things out. JMHO. Good luck!