I just resolved a similar problem with my 3w 100. It turned out that the carburetor was clogged at the screen inside the carb. Just inside the carb, under where the fuel inlet goes, there is a small screen to filter out any debris in the gasoline. I had not cleaned mine out in a year or so. I do not run any filter in the line between the tank and carb. The symptoms are very similar to yours. The engine was too lean at full throttle and would quit. I opened the high speed needle valve and the engine would not richen up. So when I got home, I cleaned this screen. Next time at the field, I had to close the HS NV back to where it was because it was now blubbery rich.