Are you running an inline filter? Ride to the roost, fueling here and there, could have gotten some shit in the tank. It don't take much to fuck up these carbs and if you are overflowing either your floats are off or the needles aren't seating or the little spring ends in the needle are fucked up.
After 6 yrs mine still act up every once in a while. make sure you check the overflow tubes that stick up in the bowls to make sure they are not where your overflow problem is coming from. that can be missleading.

When Injustice becomes Law Rebellion Becomes DUTY!!