A.M.
Hi M.,
You say he only acts out when he is "confined". Have you thought about moving him out of a crib into a twin or toddler bed? How about letting him sit at the table on a regular chair or booster seat? He is at an age when he is wanting independence but it sounds to me that his independence is being "confined" and making him act out to get you to hear what he wants. Try letting him be a Big Boy and allowing him to have some freedom.
I am also a mother of a 4 y/o girl and 2 1/2 y/o boy.
Best of luck!
~A.