ZZMT Stuttering

[zzultimate]

So i bought this zzmt from a forum member over at another rc forum. It has third cell mod with deans plug, flipped wheels, and underglow. So i was so excited on the day it was sopose to get here that I ran from the bus to my house, dropped my books, and ran for the package. I opened it, and my first impression was, sweet, this thing looks awesome. I put some fress batts in the controller, turn it on, and charge the truck for 70 seconds(like he told me to) i put it on the floor and go, it stutters like crazy. like put, put put put put......
So i pick it up and put it right next to the controller and it works. Put it back on the floor and it stutters. So i go outside and it does the same thing. The only way to get it to not stutter is to put the tx right next to the antenna and fallow the truck when it goes.

What do i do? The guy i bought it from says he tested it out right before he sent it. I've also noticed pleanty of times where he has tryied to sell it on differnt forums. I am not accusing him of scamming me, because he has been very nice and helpful, and even trying to help me fix it.

Any suggestions? Have you had this problem before. I've never had a zzmt, but wish i had, i'm missing out on a lot of fun, and i don't even know how it preforms yet!

Thanks in advance.