Kraton 6s exb rear wheels spin slower than front wheels

On about my 4th run with the kraton 6s exb, i noticed my rear wheels spin alot slower than my front wheels and they dont seem to have much power at all. My front tires will baloon still at full throttle and my rears do not at all. I figure this is a pretty obvious differential issue, do you think it would be the rear diff or the middle differential?

Also side note, both my fans for my esc and motor dont seem to be working now. I tinkered around trying to upgrade my motor fan before i realized the fan i got was not compatible. Any ideas why they both wont work now?