Well after doing it some more i found out that its not just after there dead its if i spam it.
It happens if a spam the key and the target moves then my toon just starts running like on auto run but the target isnt dead. And if i keep spamming the key he keeps turning to its target but if i stop spamming the key it will just run in a straight line like auto run untill i stop him.
Its not mobs im trying to kill here its real players that always move.