I have an old Honda self-propelled mower that is over 20 years old, used every season and has had almost zero problems with it. It's always started on the 2nd if not the 1st pull of the cord, every year, every use. However suddenly today while I was mowing the engine RPM started fluctuating wildly. It sounded like it was only getting spark (fuel igniting) every 10 engine revolutions or so. It would ignite a few revolutions, and then the engine would start spinning down, then ignite a few more revolutions, etc. It did this for a couple of minutes, and then just died completely. Fuel is in the tank, and the fuel shutoff is fully open. I let it sit for about 1/2 hour, then tried again. It seemed to start, RPM all the way up to normal range, but only for a few seconds, then it died again. The air filter could stand to be cleaned, but I tried starting it with no filter and it just did the same thing, started for a few seconds and then quit. And then on top of that the pull cord spring decided to break after trying it that last time. The mower is an old Honda SX model, the HR-215. It has 3 self-propel speeds, and also a blade clutch, so there are separate blade control and self propel control handles.