I have a 1979 John Deere Trailfire 340 that I cant get going. It starts with a Carb I have off a 440 with twin carbs. I ran it that way for a day or two it would run but was sluggish and ran a little rich. Then it stopped working all together and would only idle with the throttle wide open. I got looking and it floods on one cylinder. But I have good spark when I pull the plugs and look at them. Nice an blue spark but still seems to flood. Cleaned the carb countless times and still no differnce. It acts like my Pantera 5000 when a plug wire falls off but every time I check spark its good. What the heck is wrong?????