I have a relatively new 18.5 B & S engine that has less than 30 hours on the engine. The engine is installed on a Cub Cadet LT 1018 lawn tractor. The engine has a significant loss in power this happened suddenly while sitting still (not mowing). I noticed that the blades are not turning as fast as they normally have in the past. I have checked the linkages on the engine and the governor is maxed out fully open. The exhaust pipe is glowing red and a significant amount of flames shoot from the muffler. I have not performed a compression test or checked the valve stroke. Can anybody tell me of any obvious things I may have overlooked?

You probably picked up some dirt in the fuel tank and it's causing the needle valve to be open some. Red means too much gas.

May have to clean the tank and/or carb or just dump the fuel out of the carb.