Let me clarify...
The intermittant spark condition is happening at idle (and may be happening when revved, I haven't checked though) This condition was discovered using a timing light w/ inductive hook-up attached to various spark plug wires.
Since the problem is happening at idle w/ vacuum line disconnected, I don't think the problem is related to either the vaccuum or mechanical advance (both were working before the system was disassembled)
