I have a 1993 John deere 425. When you start it, it acts like it has no spark for the first few trys and then it suddenly starts. Starting fluid works sometimes but not usually. When it starts it runs better at low speed. The governor takes over and the RPMs go up and down at mid and high throttle. Sometimes it clears up and runs great for a while. I think it's electrical but there are alot of parts just to guess at.