[vettestr]

Any chance you found the loss of vac. since your last post? I know you needed to verify timing still so maybe... A pyrometer is available from Harbor Freight for around 15 bucks on the lower end of prices. I bought one and it tracks with my higher quality and priced unit just limited on options and bling. The pyrometer should show a temp difference on the lean cylinder/s if manifold or gasket is leaking.

Were you able to kill the engine at idle by closing the idle mixture screws? Close one side at a time but either side should stop the engine from idle.