I have a 2001 Scotts mower w/ a 20 Hp Brigs n Stratton Engine..The problem is..after it runs for a few minutes it starts to back fire on occassion..then the back firing will stop and then start again,then it will lose power and the engine will cut off.I put new plugs in it but they didn't fix it..I dont no what the model 20 hp it is..the sticker is gone..the engine has a seperate fuel pumpon the corner of the front of the engine.also it is on the starter side of the engine..