Well it started to do it gradually but yesterday I turned on the machine and it felt like it was misfiring with the throttle all the way down. I noticed a cloud of smoke, not from the tail pipe, but from a vent tube coming out of the engine. I took the valve cover cap off and noticed it too coming out of the valve cover. When the engine speed is raised, the machine stops misfiring but the smoke is still there. You think its time for an overhaul/engine replacement?