I have a 1972 Ford 2000 tractor with the 3 cylinder gas motor in it and just recently have had an issue arise and I believe it's fuel. But it will start and idle just fine. But when you give it throttle or put it under a load it will spit and sputter and try to die. But if you run it with the choke on it will run like normal. I have been through the carb, blew out the fuel lines, replaced the inline fuel filter. I hope it's not a fuel pump issue since that was replaced under a year ago. I have been through the carb with a kit and replaced the needle and seat and adjusted the float height. It is a zenith carburetor not a holley.I'm not sure what else to do or look for. Thank you in advance for any help