Kodiak troubleshooting

2003 Kodiak 400 4x4, starts and runs fine when cool. after it warms up it runs rough and will quit. under more throttle or load it seems better (like when pushing snow this winter) assume it might be a hose/vacuum/air leak of some kind but not sure.

Also, when I recently refueled and switched from reserve to On and started it, it ran for several seconds then quit. And would only run in the reserve position. I think this is entirel different issue.

Thanks