It sounds like he is acting out because he is not getting enough attention. Negative attention is still a form of attention and when you are timing him out it just makes the behavior worse I would imagine.

I would try another approach of pulling him to you and talking about why the behavior he is doing is wrong and have a talk about it. Then I would make him tell you why it was wrong and apologize. Then give him a hug.

I could be talking out of my ass here, but it worked with all the kids I ever took care of and it worked for my Mom.

Good luck.