Me too, I was given several gallons of fuel that was 12 or more years old and it worked fine. I have seen fuel that has been opened and absorb water that was bad but never ran into any that went bad due to age. The color is just dye and I have seen it go from pink to clear and it still worked. My fuel today is all in cans so I never really see the color, I'm color blind anyway so it's meaningless to me.
I would do what John said and just borrow a tank of fuel to see if that was the problem. As our temps have fallen I have had to fatten up the high end on all my glow engines, happens every year.