I don't have near the experience as most of you guys but thought I'd toss in my 2 cents with a little experience from a similar problem I had.
I had a carb that had a bead of water rolling around in the bowl. It all depended on the angle!
It took me forever to discover this. Though I cleaned it out and it ran well for a while, it did it again... till I drained and cleaned the gas tank. I don't know if it was condensation, rain or what but it was an aggravation and an engine stopper.
Anyway... Good Luck Jim! Keep us posted as to what you do to fix this, as someone else may be searching for results to their problem someday too.
Jerry
