To make a long story short, I had a blown head and intake gasket on a 20 hp Kohler Comand engine on a walker mower about a year ago. It took two different kohler mechanics and much lost time to determine the problem. I am having the same symptoms again...loss of power, missing, backfiring, and it just plain doesn't sound right (believe me I know how it should sound when it is running right). Took it back to the mechanic who fixed it last year and he cleaned carb and put in new plugs. I runs somewhat better, but still isn't right. I feel either the intake or head gasket is leaking again. My question.....what should it cost to completely have this motor rebuilt? , or, would I be better off replacing the motor. I know Dave had them for sale last year at around $1200 delivered. By the way it has only 800+ hours on it.