You may have the fuel lines connected up the way they are supposed to be, and you could still be experiencing a fuel line issue. You need to examine your clunk line to the carburator very carefully both inside and outside of the fuel tank for any holes or tears.

The issue you're describing can happen when a small tear occurs. The engine can draw fuel at idle speed without any trouble, but once you crank up the engine, the added fuel pressure allows an air leak at the hole or tear in the fuel line and the engine can't pull enough fuel to run at WOT.

Ask me how I learned this!