J.S.
Oh My Goodness, my son is doing almost the same thing. He has an attitude problem. He doesn't throw things, but he NEEDS attention 24/7 negative or positive it doesn't seem to matter. I've tried dicipline by time out, taking toys away, etc.... He really doesn't seem to care. He goes to time out, but his behavior doesn't change. He has been this way for a year now and he has a 2 year old sister. They behavior is worse when it's just the 3 of us or when family or friends are over. I made a sticker chart which coincided with a new toy if he followed the rules and got enough stickers. That didn't work for longer than a week. You just need to find that ONE special thing he likes and give it to him when he behaves. My son started kindergarten last week. He really wants me or my husband to eat with him one day in the cafeteria. So far it's working. He gets his last sticker tomorrow and we are meeting him for lunch on Friday.
Good Luck!