Thank You for your suggestion. I finally found the wiring harness after many calls to Briggs parts departments locally. It's hard to believe they don't stock that part. This seems to be a very common problem with this engine. Maybe there will be a recall, or a design change to correct this issue. The diodes they use must be insufficient for the purpose. I only have 44 hours on my mower, and now it is running better than it ever has. Thanks again.
Bob