Well, I tried it at home yesterday and it seemed fine, I took it to the field this morning, made a few last minute needle valve adjustments, and took off.
Does this mean it ran out a tank of fuel on the ground with no problems?
If so, you might just be leaning the engine out too much. Try backing off the engine way to the rich side, so that you know it's "too rich". If you are just backing off of peak "a few clicks" it might not be enough.
It does sound like fuel foaming or an air leak though.