i would cut 1 of each tapland and add 2 more Blood Crypt s and a Forest . 4 Deathrite Shaman also seems like a lot. maybe cut 2 and add an Olivia Voldaren to snag with your Garruk, the Veil-Cursed  ^{Flip  Flip} or maybe something like Liliana of the Veil or Vampire Nighthawk

Gatecreeper Vine Is the best Mana Fixer in standard IMO. kevinmtg24 is right about Deathrite Shaman . I would suggest Hellrider as a compliment to your aggro assault.

I followed your advice as far as the manabase. The thing for me about Deathrite Shaman is that he provides a lot of utility for a one drop and cutting one drops like that makes me worry about my curve.

Liliana of the Veil seems like fun for a more planeswalker heavy route, I'll consider her, as well as Olivia Voldaren .

if your going to run a one drop make it arbor elf.don't put in the gates and putting sign and blood and strangle root seems real rough. I think you need to define if you are aggro or more midrange. which jund probably wants midrange

Anything else you recommend for a Midrange build?

If you want to be midrange here is what I'd do. may not be right.take out geist, he maybe a good sideboard card because he is good against zombies. add 2 more thrags. add 4 borderland rangers to ensure you hit your land drops and thin the deck. turn 1 elf. turn two borderland. turn three huntsmaster or garruk.. turn 4 thrag or vraska is the thought.I don't know if sign in blood is good in main because zombies is so good and hurting yourself really may not be worth 3 cards. considering its also harder to cast may want to put in maybe elfish visionary.

Also olivia maybe worth cutting a single Vraska for. pretty solid. Also I'd move decay to the sideboard and play mizzium mortars. the card on overload is insane and can kill all the creatures decay can.Also if you are going more mid range, I see the mangler as being just okay because you can scavange with him.

I'd switch out the Strangleroot Geist s for Farseek s, since it finds shocklands for you, it helps fix your mana. I'd probably also go an even 3/3 Tragic Slip and Pillar of Flame . Vraska in Jund seems like more of a sideboard card, i feel that Liliana is a better choice in the mainboard instead. The problem with running 4 Deathrite Shaman s is that you don't really need or want to draw more than 1 of them. and your mana curve in the 1 slot seems pretty overcrowded anyway. Bonfire of the Damned is a good choice in pretty much any red deck, I could also see Mizzium Mortars being alright as well. If your goal is a midrange deck, i'd take out the Rancor s as they don't really fit into a midrange styled deck. 2 Olivia Voldaren would probably work, though even 1 is fine, and the addition of Wolfir Silverheart may be good.

I'm honestly torn between Dreg Mangler and Vampire Nighthawk as they both have a place in this deck, whichever you feel provides the most use.

As far as sideboarding, Zealous Conscripts is always nice, as well as Golgari Charm , Duress , maybe even Witchbane Orb

Zetsy has some good points, forgot about far seek and rancor isnt too midrangy but it does put dudes over the top and vapor snag isnt a thing anymore.