The first thing you need for a solid Cob build is a new weapon. Cob is about being in close quarters and being a fiery blender of death. You can't do that if you don't have any lifesteal! You either need to get a lifesteal Skorn, or a one hander with lifesteal. The cheapest route is Skorn, and I would also argue most effective.
I see that you have gotten rid of your Soj which is a good thing. Only use a soj if you have the dps to support it which means lotsa dps.
A lot of things you are wearing could be overhauled. You only have 4 pieces of all res, in reality only like 3.5 since the ammy has low all res. Try to shoot for 5 pieces with 60 + all res or a minimum of 700 ar.
Armor wise you are low and should be aiming for 4 k armor. Hp Wise is the same you have low vit but high life % which equals to subpar hp. Get more Vit, your chest could have tons of extra vit instead of that life %.
Skill wise you are just fine other than the fact that you are using grave injustice with no Pur (pick up radius). You need at least 5 yards on something to make it more effective, boots are a good spot for a Skorn user to get some pur.
All in all you are sorta on the right path just need to readjust and get more of everything. Stats to aim for 4 k armor, 60 k hp, 700 all res minimum.
The best Cob guide out there is here : http://us.battle.net/d3/en/forum/topic/9377379828
If you read that you should have a much better idea of what to do. If you need ideas you can look at my female doc as she is sporting budget gear and can clear mp 6 with ease, could probably do mp 7 quite easily as well.