Here we go.
Meeting someone else will really help. As will reading lots- helps explain the behaviour- and therefore deal with it.
Is there an NAS Earlybird programme near you- they'd be worthwhile.
I think the running off does get better, but it can take a while. I'll have a scout around in some books and see if they have any strategies. I can think of using a social story if your DS has enough language, or maybe a "wait" card if he doesn't. I'l have a look though.