the reason fq asked about the servo and spektrum, is that assuming he's thinking the receiver is browning out. it doesn't sound like it to me because you still have steering when you lose power. when a receiver browns out, you lose all power to the receiver including steering before it comes back on. plus the new gen 2 esc's have a pretty stout BEC (like 7 amps or something).

to me it does sound like the LVC is kicking in. once that small pack (for this truck) gets lower on juice, it doesn't have enough to supply the amp draw and kicks the LVC on. what i would do is completely turn the LVC off for a run (time it and pull the truck after 8 minutes) and see if it still happens.