I have a 2003 johnson 50 hp (J50PLSTD) that is giving me carburetor problems. Originally I wasnt able to reach WOT the engine would die out at 2500 rpms. I cleaned and rebuilt the carbs with new floats, gaskets, needles etc. Now it idles rough and smokes but I can get full rpms. When I place two fingers across the air intake of the upper carb, the engine dies. When I block the air with my hand on the lower carb it keeps running like nothing has changed. I can feel it pulling a vacuum on my fingers and it blows fuel back at me. I switched the carbs and the problem follows the carb. I've taken the carb apart and everything looks normal. I have a Johnson gauge tool to set the float height and the float is set the same as the other. Any help would be appreciated.