A few problem's with your macro:

- Death Coil uses Runic Power, so it is possible for your castsequence to become stuck on a deathcoil until you generate enough runic power to cast it.
- Your sequence uses 3 blood runes, 2 frost runes, and 2 unholy runes

(I am not sure why you are using multiple Blood specs, but you may want to use glyphed Death Strike instead of Obliterate as Death Strike provides significant self healing as well as your mastery ability blood shield)

So, remove death coil from your sequence and bind it to a separate spam key and also remove a heart strike. That is still far from ideal, so I will mention a few other suggestions.

As far as DK PvE DPS specs go, Unholy is my favorite right now. The Runic Corruption talent changes the Runic Empowerment ability to increase the regeneration rate of all of your runes by 100%, rather then a random rune, so your rune recovery is predictable and constant. Dark Transformation is the only Caveat here, but it is fairly easy to manage compared to say Rime.

If you use ISBoxer+Innserspace, you can setup what are called "steps" which allows a single key to cycle through pressing multiple keys. This is nice, because you can include abilities like Death Coil, Summon Gargoyle, and Dark Transformation as independent steps so you have a single spam key that can not be stuck on any one ability. Also, you can setup toggle modes to switch your primary spam key between an ideal AOE and Single target sequence.