Mower starts but dies in 2 secs. With the air cleaner off I can keep it running by choking it with my hand. Newer briggs 6 hp. Any thoughts please!

Did you use fuel stabilizer? Or was it just brought out of storage... anyway, replace the airfilter if it looks dirty anyway.

Sounds like the carbs clogged and needs to be taken off and torn apart and blown out with carb cleaner and compressed air.

Remove the carb. With the carb. Off, take the bowl off ( the bowl is the bottom of the carb. Where the gas is ) after you have the bowl off you will see a pick up tube that picks up the fuel from the bowl, look inside of that tube and you'll see a VERY LITTLE hole a VERY LITTLE hole, you need to clean that hole out, with a little wire. It most likley is plugged up, this is very common. Good luck :)

If you clean it with a small wire and it does not work, you will want to remove main nozzle and pilot jet and clean good all orifices need to be clean. You have a fuel starve problem.
Don