Hi folks. First post for me, pardon any mistakes. I've owned plenty of 2-stroke and 4-stroke engines, but this issue is new to me. After the summer storage (outside, but well covered and tank emptied), my 03 VMAX 600 triple 2-stroke sled will start easy with choke and coughs along at 500 rpm, until I flip the choke off, and it revs to 1700 for 5 seconds and stalls out. Starts again on one pull (w/ choke on.) This repats so consistently, that it seems as though the sled is shutting down on purpose. New gas (tried 87 and 91), new plugs (gap at 0.030), and air box and exhaust are free of critter nests. Openned the The fuel/oil mix box (presumably this is the fuel filter) and it's clean. Only 2,600 miles on sled. Tried to force it to stay running with the throttle, and it backfires and stalls. Any suggestions before I start pulling the 3 carbs? Thanks.