318 stalling while driving

My point was that power has been getting to the ECU and the coil when the key is in start.
It only intermittantly works with key in run.
Its possible there is a poor connection in the run circuit - some place between the key switch and the splice.
This poor connection or wire either vibrates loose and/or gets hot while running. (The hotter it gets the the more resistance to flow)
It is also possible that ECU is failing hot, or that the coil is failing hot. The coil's primary and secondary windings can be checked with an ohmmeter.
The ECU is not easy to test without a tester.