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I’m checking out my brother’s 5-year-old Cub Cadet xt2 GX54, with a 26 hp Kohler KT745-3085 engine, due to low to mid-throttle surging that has me scratching my head. My first thought was to remove the carburetor, disassemble it and cook it in my heated ultrasonic cleaner, which I did. Once disassembled, I was a little surprised to see how clean it looked, but I put it in the cleaner anyway, just in case there were any plugged up ports. After cleaning I reassembled and reinstalled the carb back onto the engine. All carb gaskets were still in excellent shape. It started right up, but it didn’t phase the surging one bit. I have great fuel flow into the carb, as the surging goes away at full throttle and blade engagement, and runs just fine at that level. After spraying starting fluid around the carb, the surging went away while spraying, which is telling me it’s sucking air. Gaskets are all tight and sealed, as I even applied gasket sealant around the inner edges of the carb-to-engine gasket, both sides. The throttle shaft is the only place I can think of where it could be pulling extra air (only 800 hours on engine). Could this surging also be caused by a faulty plug, improper armature air gap, or valve clearances out of adjustment? I usually have great success with correcting surging engines, but this one is more stubborn. My plan is to start with spark plugs, air gaps, and valve clearances, as this surging sounds differently than others I’ve seen with dirty carbs and bad carb gaskets. It seems there’s an occasional minor “pop” during the surge at lower speeds. Any input is greatly appreciated! Thanks, in advance!

Service Manual above see troubleshooting section.
The answer to your question is yes.