I would also ask if you are stopping while you are consuming those Gu's or other snacks. Every rider is different but for me, the more stops/breaks I do the harder it is to complete a ride at hand. For example, I usually will ride 25 miles before my first stop. If I were to change that and stop every 15 miles instead, I am conditioning my body to not work as hard and that I will break more often. When I break, it is hard to get the body back into routine. I can ride 50 miles with one break, if I were to ride the same 50 miles with 4 breaks, it would be even harder (as it is from complete rest to peak heartrate). I am in my mid 30's for reference point.

I think you are overdoing it with the amount of sugar intake. Try cutting down to one Gu and introduce bananas, oat cookies, or an orange. You prob. will feel more refreshed too (because natural products include water).

Congrats on your progress!