First question: Is it possible that the carb was not rebuilt correctly?
Second question: Do you still have the gray fuel lines?
If it still has the gray fuel lines you need to check them. Sometimes the inside of the tube breaks down and leaves a green sticky residue that can clog the lines, carbs, or fuel filter. Check the filter first, that's the easiest place to start, then check the lines. I recently replaced mine in a 99 XP; they only had the green residue on the ends, nothing in the lines, but I've seen other posts on here where it is a big problem.