Everyone's different, but you might want to try eating more frequently during your rides. Stopping every 30 miles for a sandwich or a clif bar doesn't seem like enough to me.

Here's what I do and it works great (for me): I drink a big gulp from my water bottle (I like G2) every 5 minutes or so. Yes, that is frequent, but it keeps me hydrated. Of course, this requires the ability to drink while riding and not everyone has mastered that skill. I eat a bite of a powerbar (my preferred ride food) every 15 minutes or so, again requiring the ability to do that on the fly. On organized rides, I'll stop at each rest stop, refill my bottles and eat something they offer--usually cookies or bananas or pbj. Then I set off again and start with the 5-15 minute routine. Sometimes I have shotblocks, but they are like candy so I have to keep myself from eating them all at once!

This works for longer rides as well as my more usual 1-2 hour rides, but I find it essential for distances over 40 miles to avoid bonking.

Right after the ride, I'll have chocolate milk (you can do soy if you prefer) and something salty like potato chips or pretzles. Within 30 minutes or so I'll try to have something more. If my ride ends at home, I make myself a smoothie with bananas and chocolate soy milk and ice.

I do eat meat. I used to be a vegetarian, but found myself lethargic nearly all the time, as well as 20 lbs too heavy. I started eating meat and lost 20 lbs and gained much more energy. I've always had low iron (I can't ever seem to pass the iron test for blood donations) so a non-meat diet was not working for me. Not to say this has anything to do with your diet; just reporting what has worked for me.

Best of luck!