1999 Dodge Dakota Power Module

My Dodge Dakota died at 65mph on the freeway with no warning or no check engine. Towed to the dealer and he said the PM (computer) was bad. 2 days later I called and he said the replacement was bad an ordered another one. 2 days later I called and he said they were waiting for a coil and the truck would be ready. I wonder if it was the computer or just the coil, if you lost a coil while driving wouldn't the motor die immediatly also. They charged me for the computer and coil. Just wondering if I was charged for a misdiagnoses.
Thanks