I try to drive my 6400 at least once a week, but when it gets hot (180-200 degrees) it gets a really sloppy idle. The truck runs like new going down the road and even gets good gas mileage. I might rebuild the carb, but here is the question. My rig still has the governor under the carb. Can a vacuum leak develop on this device that might be causing my poor idle? Would it run better without the governor? I drive like an old man, so I'm not really worried about over revving the engine. Any thoughts?