Now that's where I'm baffled about mine. The choke has to stay shut even when it's warmed up to be able to run. If I open it up at all it dies. Of course the previous owner compensated for this by backing the mixture screw almost all the way out. That, of course is just a cover up to the real problem, which has yet to be found.
How about the head gasket? I got thinking about it and like I said earlier it idled really well when cold but when it warms up it does that itermittent growling/shaking at idle. It was very apparent that it instantly got worse when it reached operating temperature, which leads me to think it happens when the thermostat opens up. Would a bad head gasket lead to a bad vacuum leak? And shouldn't my oil look like a milk shake at the bottom of the dipstick? Right now it doesn't and doesn't smell overwhelmingly like gas either. I will do a compression check to see how it is doing as far as the rings are concerned. I did notice alot of oil on my spark plugs when I replaced the old ones.