I installed an Edge Performance Chip in my '05 Chevy Duramax Diesel Truck and 35,000 miles later replaced two sets of #2 and #7 Injector Harnesses. Is there any relationship or is it just a coincidence?

The edge has nothing to do with the injector harnesses. If you search for "ice pick" you'll find out whats causing your 2/7 issue. Pretty common on the LLYs.