You need to go back to the drawing board a little bit. I'm not sure what you mean by "tuned" but your deck looks really inconsistent.
Here's some issues right off the top.
Land - way too few, even the most aggressive decks don't run less than 20 lands. You're deck tops out at 4 and has serious activated abilities to invest in. You need a minimum of 23-24 lands.
8 Forest - 3
4 Overgrown Tomb
5 Swamp +4
+2 Golgari Guildgate
+4 Mutavault
Creatures - Deathrite shaman is not a standard card. I know it's standard legal, but it's performance in the format is very lack luster. You're counting on grisly/commune to get stuff in your yard to exile, but you also want to scavenge? these strategies are kind of counter productive.
I think this deck is more of an aggro deck. You should really be looking at things like Experiment one and lotleth troll. A set of elvish mystics is okay to ramp to a 3 drop on turn 2, if you're playing dregmangler or something, or even corpse jack on turn 3.
Despite how it looks Jarad doesn't play well with scavenge and other exile mechanics from the yard. You basically make him weaker every time you scavenge something unless you scavenge on to him. You're better off just making bigger creatures with lotleth/exp 1/varolz.
Slitherhead is just too weak. The only reason you want it is to scavenge it and that means it does nothing for you on the board.
You may or may not have enough devotion to turn on nylea. I don't know if the buff she provides enough reason to play her even at a 1 of.
Desecration demon. Not really the right deck for desecration demon, he belongs in a control/midrange deck.
Honestly I think I'd cut all the ramp, unless you go big golgari aggro, kalonian, mystcutter. Then maybe something like reaper of the wilds or desecration demon would also make more sense. I thin your one drops want to be some combination of exp 1, tormented hero, rakdos cackler.
4 Deathrite Shaman
2 Elvish Mystic
4 Slitherhead
4 Scavenging Ooze
2 Sylvan Caryatid
3 Varolz, the Scar-Striped
4 Corpsejack Menace
2 Desecration Demon
2 Jarad, Golgari Lich Lord
1 Nylea, God of the Hunt
Spells - run grisly or commune not both. (hint, grisly is the right answer in this deck). Drown in filth isn't what you need here.
Abrupt decay hero's downfall, those are the cards you need to be running for removal.
The bow is unnecessary. It's very flexible, but does a lot more work in a control or devotion shell.
4 Grisly Salvage
1 Bow of Nylea
4 Commune with the Gods
3 Doom Blade
3 Drown in Filth
Please try to keep in mind that I'm pointing these things out to help keep the deck consistent and on a plan. Like it or not you're on an aggro plan. You're trying to kill people with aggressively costed creatures that can get in damage early but have enough resilience to stay in for the long game. Scavenging ooze, varolze, corpse jack, are all aggro cards. You could go "big" with these cards and do something like mystcutter hydra or kalonian hydra. That chagnes the curve of the deck a little. But these counter doubling interactions are just cute and generally not considered consistent enough for really well rounded decks.