Still having trouble with my Gehl 4500. I installed an electric fuel pump to alleviate any suspected vapor lock issues, set the regulator to 4.5 PSI. The issue that I still get it that the engine will stumble for 2 seconds and die when a slight load is applied. It can happen during turning, lifting, dumping, but so far never when driving in a straight line. If you catch it stumbling fast enough, you can throttle down and save it from dying. Then slowly throttle up and she will be good for a while. It is a very difficult situation to be in when you need a machine to do it's job. I have good spark, engine runs very nice, no misfire, spark plugs all have a nice even burn on them. Ford 1.6L Industrial, Zenith carb. Not sure what to do, I am very frustrated. Could I have a bad or going bad vacuum advance?