Yeah, I've been reading a bit about the Feingold diet and briefly about GF/CF (I'd never be able to pull that one off though -- WAY too much work) and a soy elimination diet. I've been trying to cut out a lot of HFCS, too, and I'll try to stick with that.
My plan is to cut out a lot of HFCS and limit it to maybe one 20 oz. pop a week. I would also start out by cutting out dyes that are pretty well-known, like the numbered dyes (such as red dye #40), and a lot of soy. I don't eat too much soy, but I would limit it to like one thing that contained soy per day, maybe, and work from there. I have a tendency to just jump right into things and try to do everything and then I end up failing at it, so I'm trying to be really careful about taking it one step at a time with this and just starting gradually.
Oh, and I feel that I should add that by LO is exclusively breastfed.