Diagnosing cylinder misfire

Haven’t tested the ballast resistors that we took off, not that it would mean much but the coil was replaced a few days ago. But could certainly be bad out of the box. My son just tested the voltage regulator and it’s showing that it’s putting out 15.5 volts on a fully charged battery. And there again the voltage regulator was replaced at the same time as the coil and resistor. But if it’s putting out that kind of voltage we’re leaning towards that as the culprit.
Coil. Smp ballast resistors usually dont fail two in a row.