Hi, I would say, it sounds like you may well have some detritus in the carb jets, fuel lines and perhaps, float inlet valve. I can hear your frustration and resignation, I have been there. If you can take the carb off, literally, used compressed air, blow out all of the fuel ways, nozzles, jets and change the internal filtre for a start. if the tank was or is rusted, this won't help matters as even a micro particle, will potentially, clog up the carb jet(s). In addition, check carefully for air leaks, especially around the base, the gaskets can, if not tightened down correctly or isn't sitting on the manifold flat, can (will) draw in unwanted air, which will make starting, running and performing, a pain!