He's not a great listener, although his 1st grade teacher told me that he could chat non-stop with attention directed elsewhere and still respond appropriately to whatever she might have asked. He is impulsive and always has been - we've been working on thinking about things before doing/saying them. He's quick too, he jumps around from topic to topic and back again - it's hard to keep up if you're not used to it.
That sounds just like my brother-in-law. Unfortunately, he's 32 and still doing it!
I'm sorry that I don't have anything constructive to add but I am curious to hear any techniques. I have two boys who talk non-stop too -even in their sleep!