Sam,
I've got a new /simular problem with a Slow Stick that I just built. The motor runs fine for just a little while and then cuts out, just like when the batteries are running down. I have fought with it for a couple of days now. I have tried a new battery, a new reciever, new servos, a new speed controller, everything except the motor. I am about convinced it must be somehow related to noise spikes coming back from the motor. I plan on swapping the motor this week end and trying that. I sure am stumped by this problem. It sure sounds like we have similar difficulties. if you nail down the problem let me know and if the new motor fixes my problem I will sure try to relay that info to you.
Buck