Terry or other guys using the Kawasaki engine on there exmarks. I have the 21 hp kawasaki on my lazer z hp, the engine is sputtering on small slopes, did a tune up oil, plugs, air filter, fuel filter and oil filter. Still looses power on some hills, dosent do it all the time. The longer its been running the more likely it is to sputter on the hill. Any ideas before I take it to the Lawn shop.