Brushless motor/interference?

[littlened]

Just got an Orion Vortex ESC and 4.5t brushless motor. fitted them to the car using the standard receiver and a set of brand new orion 5100 nihm batteries. At first the car cut out all the time, which I figured was down to the tamiya battery connections, I've order some better connections which are more suitable, but in the meantime I've connected the battery to the car using 240v connections, so they shouldn't cause any bottleneck. I'm finding the car runs lovely now, until it gets a short distance away from me, and then it either starts twitching itself or wont respond to controls. I have to walk closer until it responds.

I've tried moving the receiver a little which did improve the distance, but I'm really restricted as to where I put it as there's no room left on the chassis.

I'm running a 27mhz AM setup.

Can anyone shed any light on this problem? could it be interference?