Just my two cents worth. The fan you show in the photo (in my opinion) is to close to the radiator. Being that close it can't effectively draw air through the radiator. It should sit back a bit more. If your flex fan works sitting back at 2 1/2 inches, there's your problem. I had the same problem once. Moved the fan back and my engine ran cooler. Also run a 6 or seven blade fixed fan and keep it at 2 inches or so. See how that works for you.