Chronic Flame Sensor Failure - Furnace and Water Heater
Check with your local natural gas utility. That's the company that actually delivers the gas - the same one you call for leaks, but don't call the emergency line for this problem. They may have a pattern of problems, and you would be another point for analysis. Or they may even have a solution.

While different, this reminds me of problems in my area (Maryland) years ago where lots of people got copper b water pipe pinhole leaks. Eventually it was traced to the chemicals in the water and the problem was resolved, though not until after plenty of people (myself included) had to pay to fix their pipes.