HALP! I need advice - TankSpot
This is where this post belongs, though this forum is the right place for discussion of methods in general.
I'm surprised you push to 4 stacks on the impale, that seems to be asking for trouble. If you're having trouble only after re-acquiring his attention though, I'm more inclined to believe it is a problem with healers adjusting to the change, while managing snobolds (who slow movement and interrupt casts) and fires. They're simply having trouble keeping consistent heals on you in all that mess following the switch of targets (i.e. depending on the healers hots may not be up, or bubbles are slow to be applied).