Dart electrical problem

I've written skads on troubleshooting these. "Do a search." I get tired of typing

As Red said, "could be anything."

This includes poor supply voltage due to the ever present bulkhead connector, bad ignition switch, and several connectors along the way

Could be the connector right at the ECU, or the distributor connector

Wear in the dist, the pickup or the adjustment. (gap.)

MAKE ABSOLUTELY CERTAIN the ECU is grounded!!!

GET A MULTIMETER. We can walk you through some tests.

What do you have for test equipment, service manuals and diagrams?