Had my 1996 Johnson tiller out on the lake yesterday for the first time in a month. Ran fine then all of a sudden lost all power and died. I was able to restart and limped back to shore manually pumping the primer to get the engine gas - otherwise the engine would lose all power and die. Let sit for a while then went out later to try again. Ran better that time - I didn't have to use the choke to keep engine running but I only had about half power in full throttle. Any suggestions what is wrong and how to fix??? Thanks