Hotter plugs will help somewhat, as long as you don't do much heavy load pulling at full throttle. If the tip of the plug gets hot enough to pre-ignite the mixture before the spark happens, it causes detonation, and possible serious piston and/or valve damage. Hotter plugs were recommended for engines that were primarily used for short trips and stop and go driving, with little or no highway mileage to burn deposits away. I'd begin with a set of new, or cleaned-up mid-range plugs and look for over-rich fuel conditions before going to a hotter plug.
Jerry
