xmod problems, or is this normal?

[silver 4.6]

first of all, me and my friend were racing, my car wouldnt turn left when our controllers were close together, and had alot of lag from my controller to the car. i tightened all the wires and the antenna and it seemed to go away for now.

second, when batteries die, does your car just all the sudden quit? my car seems like a battery sucker, it'll run for about 15 minutes and poof, it just slows down to a stop.