Hello and thanks for reading this post. I have a 2003 Arctic Cat 250 4 X 4 Utility ATV. It has been running very well all summer and into this fall....until a few days ago when it lost power at about 1/4 throttle. I checked the air flow and found no issues there (I replaced the spark plug at an oil change 2 months ago). There was about half a tank of fuel and the fuel valve was in the "On" position. This issue first happened Thursday evening when it was about 32 degrees outside. When I got off work Friday afternoon, I fired her up and she ran perfectly without me doing anything except starting and riding it....it was about 54 degrees on Friday afternoon. Saturday morning (32 degrees), I fired her up to saw and haul some firewood and the issue came back. It started fine and ran normally for about 3 - 4 minutes at idle and then riding out to the woods at 1/4 throttle and above, sputter and putter, as if starved for fuel. I limped to the woods in first gear and then back home the same way. Letting it sit for a few minutes would permit it to run properly (all the way up to full throttle) but only for a very short while and then it would sputter at 1/4 throttle. I figured maybe there was gunk in the carb or perhaps a cold weather related vacuum leak in the carb......so I swapped the carb out with a clean and properly functioning spare carb that I keep on hand (I also checked the fuel flow in the fuel line and it was fine and there is no fuel filter in the line)....and it ran perfectly for the rest of the day.....even hauled 3 cart loads of cherry firewood chunks with it (probably 500 pounds in each load) up a steep incline and it never missed a beat (it was about 40 degrees by that time).....so I figured it had been a dirty carb. This evening (45 degrees out) I fired her up to put out a little shelled corn for the deer and after a few minutes of riding, (slowly puttering around) the issue has returned....so I had to limp back home in first gear. It acts like it is starved for fuel.....so I even filled the fuel tank up and after that it would actually run in second gear but it still sputtered starting at 1/4 throttle.....but the full fuel tank did make a slight improvement in performance. Any ideas on things to troubleshoot would be greatly appreciated.