How do i fix this gas knock

I'd try a different brand of fuel first. If that doesn't do it, try ethanol free fuel at 87 octane. You can then try having the engine scanned for malfunctions. At 289K, the engine it getting long in the tooth as well as being 20 years old. Personally, If nothing else helps, keep using premium fuel until it gives out. Then it is decision time. A re-manufactured engine or the price of another truck. I take it for granted the engine has been tuned with new plugs, etc. recently.