First, how wide open is the barrell in the carb? At idle you should have no more than a small opening. Enough to put a needle through (sewing needle). Next I would check the fuel circuit for a restriction that is making the engine run extremely lean. Your comment about the engine having no power and quiting when you open the throttle tells me you are to lean. Since you have not changed the needle setting from prior good runs I suspect a lack of fuel flow to the mixture needle. Also check your fuel lines for a source for an air leak. That will also cause a lean mixture.