What about the governor system?
Thanks MS_SURVEYOR for your response. I disassembled, soaked, cleaned, checked the carb. Still seems great. Great flow from fuel tank through the bowl drain. It starts and runs until the engine has been loaded for about a minute. Then it loses power and slows down. If I continue mowing, it dies. I noticed the governor external linkage was dirty so I tweaked it back and forth. I was able to duplicate the poor running condition. Then I sprayed the external linkage with carb cleaner followed by silicone. Unfortunately, I got no improvement. The external governor linkage sure looks better though. <gr>
Anyway, I am unsure what adjustments or parts in the governor system might be related to engine temp. Also, what serviceable parts might I check? Is there a ready adjustment? What about the governor spring attached to the throttle butterfly? Could that be stretched / damaged when I removed / replaced the carb?
Thanks in advance for any suggestions.