Ok, #3 cylinder dropped out again during idle. But... I found an air leak in an interesting location that was causing the problem. The vacuum diaphram on the petcock had a tear in it which allowed air to go through a groove in the plastic part that is between the two rubber peices of the diaphram (groove allows diaphram to displace air in the petcock), through the tear and into the vacuum hose that actuates the petcock. I replaced the diaphram and that solved the problem. Just thought I would put that out there for anyone looking for an air leak.