Small Engines (Lawn Mowers, etc.): Briggs and Stratton 19.5HP engine, craftsman riding lawn mower, briggs and stratton

Question
My Craftsman riding lawn mower began surging during idle. I replaced fuel lines and fuel filter and it still surges. Sometimes I can pull the choke out half way and it will run fine for awhile sometimes.  It has also backfired once. I would appreciate any help you can offer. If you have any questions let me know and I will get right back to you.
Thanks,
Ryan Sanders

Answer
Hello Ryan:

There are Several Possible Cause for this Problem. 1- The Fuel Shut Off is Not Working Properly. 2- The Carburetor Needs to be Cleaned and Rebuilt. 3- The Valves need to be Adjusted. Send me the Model Numbers Off the Engine, Please. With these I can Locate the Proper Manual and Better Assist you. Thanks.

Respectfully

John