I have a MTD riding mower, that has a 13.5 Briggs and Straton engine. It will start for a few seconds than it dies. I replaced the fuel filter and fuel line. Does any one have any idea why.

Sounds like you didn't empty all the gas out last season.

The carb is likely gummed up and needs to be cleaned.

Next time use Stabil in your gas and use at least the mid grade.

Hi,
Hate to answer with a question, but the engine numbers would be helpful. If is is valve-in-block or overhead valve makes some difference. A clogged carb will still do the same; cranks on choke but will die on run. It can often be run on partial choke to use the "abrasive" effect of gas flow to clean it.
Peace,
Clarke