Runs, drives, dies

Here is an older thread with some good testing steps. Read this thread, mostly the post #4 by @67Dart273 and get familiar with the tests you should perform, then get it acting up again and unplug the distributor connector and try the tests. If it still does not spark you can rule out a distributor issue, if the test is performed correctly. To verify the test, reconnect distributor and make sure it still won't spark while cranking, and then unplug the distributor again and repeat the test.

Diagnosing Distributor - No Spark Chase