Has anyone ever successfully rebuilt a 540xp autotune carburetor?. i have 2 ea 540xp and both saws pop and skip and bog down when first started. after warms up for a minute they both run fine. Its an Walbro AT 2 729 Carburetor. I bought a new carb but skeptical to put it on cause it has to be programmed at a husky dealer. any help would be appreciated. Thx