The burning up of the coils might be caused from a defective ignition module.
The ignition module functions in two modes. These are the start and run modes. When starting the engine the ignition module allows full battery voltage to the ignition coil. This ensures that there’s a hot enough spark when starting the engine cold when the fuel mixture is rich. Once the engine starts and the ignition switch moves to the run position, the ignition module switches to the run mode. The ignition module then steps the voltage down to the ignition coil. This is done because once the engine starts and the charging system comes on line the voltage from the alternator is too high for the ignition coil.
So the problem might be that the ignition module is failing to switch to the run mode once the engine starts, and higher voltage from the charging system is burning up the coils.
Tester