Lincoln LS 2001 V8 dies while driving

My husband was rear ended in December, he died six days later, I took the car in after the funeral for body work. When I got it back it had a horrible quirk. It dies in traffic, the dash lights go out, the electrical system goes off, the car stops getting gas, within a few seconds it's too dead to lock up the doors with the button I have to manually lock them, call a cab and a tow truck. Four times I've had it in, they can not find out what is wrong, the last time they wiped off a "possibly " corroded wire, the time before I bought a battery, the first time they replaced a valve cover and gave me two new spark plugs because there was some some smoke. It happened again this week, instead of towing, I waited, the next day it started and drove like nothing had happened. It happens about once a week. Twice it has warned the day before with a quick flash of check charging system, but not on the day it dies, when it dies it says check traction then goes out right away. I've taken it to our local Lincoln dealer, they are baffled.