motor runs great but shuts down ?

by chuck patch
(uniontown,pa.)

i can start it up, run full throtle sometime about a mile then it shuts down ,then before it shuts off i go back to idle posistion on throtle and if i goto full again it runs full,and does this over and over,is it my fuel tank maybe a problem ,or something else please help ,thanks,9.9 gamefisher sears outboard two cylinder