Does your spektrum receiver cut out when you apply throttle when it is on the ground? Is this only happening when you use the NiCad batteries? Try your lipos.

When the truck is on the ground a lot more amps is sucked down, than when the wheels are lifted. A high amp draw lowers voltage, which could be enough for the spektrum to cut out due to a too low voltage input from the esc.

What happens when you slowly accelerate? Does it move?

The cure for the spektrum problem is attaching a capacitor to the RX to store power for when the voltage drops. Just attached something like a 16V 4600uF capacitor to a free spot on your RX.