What does it mean, when, only, when i am pulling something or carrying something (under load) on 1996 350 big bear will the bike start choking or sputtering. But if im riding it normally by myself, it rides normal.

 

Change the plug, just in case it is that. However, probably carburettor mixture slightly out, either weak or rich, check the colour of the plug after a ride, black and sooty means rich, possibly choke stuck slightly, white plug nose means weak, often due to dirt in a jet.

 

It sounds like it's running lean as generally more load on an engine will require more fuel and that's the case you're describing. As merryman stated check and/or replace the spark plug. The color will give a strong indicator to the current A/F mixture the combustion chamber is seeing.