Did the radiator coil have nothing to do with the problem? My brother has the same problem, but with a Volvo, he even took a new
Volvo ignition coil for it, but didn’t fix the problem. We weren’t able to figure out ourselves, so we decided to take it to the mechanic. Fortunately, they were able to fix it. The unfortunate side was, I wasn’t able to know what caused the problem.

So I guess I could just relate the conclusion with that of yours.