After running for fifteen minutes the engine shuts off

This sounds like a crankshaft angle sensor gets hot and quits which will make the engine stall. Here are two guides one to show you what you are in for when changing the sensor out and the other which will run you down all most of the possibilities:

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

and

https://www.2carpros.com/articles/engine-stalls

Here is the location of the sensor,l they call it an engine RPM sensor.

Crankshaft Position Sensor - 06A906433C - $154.95 list you can get it cheaper on Amazon.

Check out the diagrams (below).

Please let us know what you find. We are interested to see what it is.

Cheers, Ken