Well, it's used near the house so it's only a little OT. Anyway, it starts and runs fine when cold. But as it warms, the RPMs continually increase until it is running extremely fast. The visual problem is that the carb throttle plate is against the idle adjustment screw when cold, but when hot the plate never returns to the idle screw. When turned off, it immediately returns to the proper position. The throttle cable is clean and loose. The throttle plate has a coil return spring that has been cleaned and lubed. All fuel lines have been replaced. So the problem doesn't appear to be anything sticking, rather sucking fuel/air faster than the spring can overcome. There is no apparent vane governor like mowers have. Any ideas out there? BTW, it,s a Husqvarna Mondo.
KC