My push lawn mower will start, but quickly sputters out. I removed the air filter to see if this was the culprit, but the results were the same. What next?

Find and remove the fuel filter, also remove the gas cap to make sure there is no vacuum in the tank. While removing the filter flush the tank dry and refill with known fresh fuel.

We just bought a poulan pro lawn mower last year, and this summer we're having a lot of trouble with it.. if it starts, it will go about ten feet, then it will stop/stall.. or it just won't start at all.. and that's where I am at now.. I can't find the owners manual.. please suggest