CD - as I said before diet has had a profound effect in my family, particularly for my child with the most issues. But I really strongly believe that you need to do a proper scientific elimination diet. Even prehaps reading the online portions from the handbook we have used might help you :

http://www.sswahs.nsw.gov.au/rpa/allergy/resources/foodintol/handbook.cfm

My personal take on all of the more out there things that seem to help with ADHD and / or ASD is that these are people who are both physically and mentally very sensitive. It's easy to upset their apple cart and see a negative effect from things that just don't impact other people (diet, electromagnetic fields, whatever). It's easy to think diet has "cured" ADHD. Personally I think that is rarely the case. But you can eliminate a stressor that is exacerbating everything and see significant day to day improvements as a result. For us (and anecdotally I think it's quite common) the diet has had the biggest impact on hyperactive/impulsive/mood related issues, not so much on the inattentive portion.