This is an article on testing coils that i found try it out. Testing Coils..

 

This is a classic example of a failing crankshaft position sensor. The motor turns off because the ecu only powers the injectors if it recieves a signal from the crank sensor. Remember, its the negative thats turned on and off for the injectors. Injectors always have positive connected to them and the ecu wont turn on the relay to provide the positive until it confirms the motor is turning.

 

It might be what i found my car to be.
Check by the shock mounting on the Lh side of the car if you sitting in it.
It has a part no. 39500-22000. Its called a potentiometer idle control.
I dont know if your cars have it.
My car is map based.
Its a small sensor.
This caused my car to stumble and eventually switch off after 20-30 mins if driving.
You can look in my thread and read. Maybe same symptoms.
Anyways hope you come right soon.