vampirc knockback and all they do is kite me untill i catch up to them then knock me back and they when chasing them i pull more packs i got one traped in a corner and killed him real quck but cant seem to catch the other 2. their life regains back to full b4 i can reach them.
What class are you, and what level? Since there are so many skill combinations available, and with new ones opening up rather often, we need a bit more to go on.
Run past them or reset the game. It is a baseline that you won't be able to kill all randomly generated elites. In Diablo 2 there were champions with melee damage reflect aura for their minions, and if you were a paladin/barbarian, you'd die from your own attacks in less than a second. There was no way to deal with those, you had to avoid them.