I replaced everything but the coil and yet I had a weak erratic spark
My coil looked ok, no cracking. I checked it with a ohm meter and the readings were not as indicated
I replaced it and that did the trick
Good luck
On that note, ohm readings are not very dependable for coil ttroubleshooting. A few partially shorted turns in either primary or secondary will never be detected, and moisture ingress causing a high voltage leak won't show up many times on a meter, either Even a "Megger" I have one 500V and 1000V and it is not enough to test coil insulation--as they generate much more in operation
If you don't have some form on specialized coil tester, you have to just "guess."