Is this rider or push mower? How long has problem been going on?
Was it run low on oil? When it stops, will it refire immediatly?
If push mower, does it have a float bowl on the carburator that you can remove and check the needle valve and seat?
It is a push mower and this is the first use that I noted the problem. To my knowledge it was not run low in oil. It refires immediately most of the time but not all of the time.
I don't know what a float bowl is.
The float bowl would be the bottom of the carburator. If I had the sears number example 912-88999, I could see what carb you have, but here is a site with a basic carb. http://outdoorpowerinfo.com/repairs/briggs_walbro_lmt_carb.asp