Regarding speech, I have AS and was an early talker, but with some echolalia mixed in.
As for the GF diet - I have recently started this, and for the first time IN MY LIFE I am not tired all the time!
I was always tired, even as a young child, no matter how much I slept and doctors just fobbed it off as first anaemia, then depression and then just stress.
But within a few days of stopping the gluten, I suddenly wasn't tired anymore and can concentrate a lot better.
When I do cheat and have a little gluten, it makes me tired within a few hours.
I am also on a low-casein diet which helps - I can't have milk or ice-cream or soft cheese etc as they upset my stomach.
I also can't have pulses because they upset my stomach too, along with certain fruits.
Interestingly, I read recently that soya has similar proteins to casein, so perhaps that is why I have a problem with pulses?
I have to drink rice-milk as it is the only safe equivalent for me.
GF diet, or even GF/CF is worth a try.
There is an excellent and very user-friendly book on this by Luke Jackson.