We inherited a small lawnmower with the house we bought. It's a 21" self propelled walk behind Troy Bilt, not very old, maybe 5 years. I have changed the air filter, oil, and checked the plug. Was running well, but has been a bit sluggish lately, and even konked out a couple of times, but it restarted. Is there anything else I should check? It just seems like a fuel system issue. Am running fresh 87 octane, but it has ethanol in it I'm sure. Will non ethanol gas help? Is there a fuel filter on it? Any suggestions are appreciated. Thanks, Ed