Mower is 10 yrs. old. Running fine until 2 weeks ago. I detected a slight skip while mowing. The next time mowing, the engine began skipping and choked off. Puff of blueish white smoke from muffler. I have installed new plug, fuel filter and battery. Now when I crank it runs fine for about a minute and then begins to choke down again. Right before it chokes down it runs really rough and starts smoking. Any help with this will be greatly appretiated.

Kelly, June 2012