The problem is the stabilization of your blood sugar and the timing of when you're eating relative to your run. It can spike and drop, whether before or during if you're consuming just carbs. You want to take in 50g of carbs per hr, before a run. A Honey Stinger Waffle only has 21g of carbs (and 7 grams of fat, 1 gram of protein). Any sugar in your coffee? Thus, if you're eating 1 hr before, take in 50g. 1 1/2 hrs before= take in 75g of carbs. 2 hrs before=100g of carbs. If you add more protein (put peanut butter on your waffle) it will help to better stabilize your blood sugar so it's not spiking and dropping quickly.
As others mentioned, you should have enough stored glycogen for a typical long run. If you're maximizing your glycogen stores (500g+), we normally have enough for ~22 miles (at marathon pace) or more going at an easy run pace. Hydration is important too. Probably a lot of runners aren't hydrating enough during the winter. Again, energy swings are a blood sugar and timing issue and then your body shifting to metabolize more glycogen to help raise your blood sugar again to feel better. I personally have a tendency to hit an "energy low" around 1hr 40 min on my long runs when I'm intentionally not fueling (which helps to be a better fat metabolizer).
Otherwise, listen to your body on fueling frequently throughout the day and eating enough, esp immediately after runs (same again of aiming for 50g per hr run, plus protein= 4:1 ratio of carbs:pro).