Glad you found the problem. A loose pressure fiting will give you the same results as one that is partially clogged.

While you are at it, and since you found something loose. check/tighten all of your head bolts, and crankcase bolts. Loosen the crossbolt that holds the carb in and pinch the carb down while retightening the crossbolt. This should eliminate any other leaks before they become a problem.