mower will not stay running

my mower worked fine a just a few weeks ago and now it will start but stops after only few minutes running. it has gas ans oil. it is a toro ans yes it is probably 17 years old. this happened last year but before the lawnmower repair rush started at the repair shop. It was 50 bucks and I am sure it can be and easier fix than that. Anyone there?

i cleaned the carburetor . it works fine now

Many no start problems are fuel related and the ethanol in gasoline contributes to the cause. Try using Marine Formula Sta-Bil in your fuel. I add it to the fuel container before I buy gasoline so all of the fuel is treated all the time. I decided to put it to the test and left treated ethanol gasoline in my generator for one year. After sitting for a whole year I was able to start the engine and it ran normally. I then drained all the fuel out and used that fuel in my riding lawnmower and the lawnmower performed flawlessly. Is this proof that Marine Formula Sta-Bil works? To me it is and I will continue to use the product as long as it's available. YMMV.