I'm still dealing with this issue although I haven't been driving he car the last few weeks. I put in another known good coil. It wouldn't start (at least easily) when hot again. I checked the voltage across the coil and it was 5V/8V RUN/START. I should have tried applying 12V directly to the coil to see if it resolved the problem. Here are some more numbers from my testing. All engine bay wiring, distributor, ECU and ballast are new. I'm not sure what to check next.