I get runners occasionally when trucking through a bunch of mobs and the 'main' gets stunned or trapped.

I don't use roads, I ride straight line through mobs and pull an aggro train. Start killing only if stunned/dismounted/etc ... : )

It's like the followers don't realize the main isn't moving anymore. It's not a lag problem either, because the toons just keep going in a straight line forever and never stop.

In my leaderless setup, I have the WASD as the primary movement keys for all toons and the arrow keys as secondary movement keys for all toons.

I use a KeyClone strict whitelist, and that passes only the arrow keys for movement. (among other things.)

When a mob starts fighting in the middle of my follow group, or if I want them to stay put, I press the down arrow and they all back up and stop following.

If I need to turn them all to face something, I'll use the left and right arrow keys.