Before I started changing $100 parts, I would want to make sure that the part was faulty beforehand. During your testing of the stator and rotor, what was the resistance reading ? Did you insulate the brushes from the slip rings before testing, if not you most likely did not get a good test of the rotor. When you have the engine running and have a voltmeter connected to the battery, does the voltage go up to 13-14 volts when the rpm's are increased to around 4000 rpm, or does it stay the same ? Have you checked the connections of the major cables for security and for corrosion ? When your starter doesn't work, do you have low battery voltage ( headlight and other lighting dim), or do just have a starter problem when it's hot ? Throwing parts at an electrical problem without having some sort of troubleshooting plan, can get quite expensive, and not get you any where closer to solving your problem. Sorry about sounding a little harsh, but I don't know how many times that an owner just starts throwing parts at a problem, and then gets frustrated when it doesn't solve the problem, and not knowing anything your technical background, I can't tell if you are going about this in a methodical way or not.