when the engine dies, does it sound like the rpms are decreasing (like a heavy load on the engine), therefore killing the engine?
If you have no wires hooked to it, unless the solenoid in the trans is stuck on, I don't think that would be the problem, because the lock up feature should not engage by itself. It takes 12 volts to lock up the converter. I have a toggle switch on mine that supplies current and flip it on when I drive over 45 mph, locking up the converter.