When a child is a picky eater, he is often making a statement. 

Perhaps your son also has some food intolerances/allergies. Perhaps that
is the root of his "picky eating." Because he is so taken with pasta
cereal, and macaroni, I would like to suggest that you get blood tests for
celiac disease and grain sensitivity. Some celiacs are addicted to gluten.
Your boy sounds addicted. 

That may sound like a strong word, but let me explain. The pepsin digests
of milk and gluten result in peptides that are psychoactive. In normal
people, these peptides are further digested into amino acids, then absorbed
into the bloodstream. In some people with food intolerances, because of
damage to the intestinal wall, these psychoactive peptides are absorbed
into the blood, without further break-down. They may circumvent the blood
brain barrier, or they may swamp it. In either case, when the peptides
reach the brain, they act in much the same way that opium does, and attach
to the same receptors in the brain. Some celiacs aren't very interested in
eating if they can't get that satisfaction.  Even if your boy does not have
celiac disease, I would have him tested for other food intolerances.  

If he demonstrates antibodies against either milk (casein) or gluten
(gliadin), I would restrict both from his diet. 

For further information, you might want to look at the posts of Dr.
Reichelt, and some other researchers exploring developmental delays.
see:

  http://www.panix.com/~donwiss/reichelt.html

For more general info see:

  The Gluten-Free Page:  http://www.panix.com/~donwiss/
  The No Milk Page:      http://www.panix.com/~nomilk/

I hope this is helpful.

Best Wishes,
Ron Hoggan   Calgary, Alberta, Canada