Another thought would be to check the vacumn advance on the distridbutor to see if it is functioning properly. I had one once that was stuck and had the timining fully advanced right from idle! Not knowing this I retarded the initial timing. This made the thing run somewhat in the same way you described that yours does. Take a timing light to it and see if the timing advances when you rev it up. If it doesn't, then what I described is the problem! This one had me scratching my head for several days! :confused:
