You need to get someone to check the firing KV of the ignition system using a oscilloscope to find out what is really happening, check the resistance of the coils against each other IF one has a lower resistance than the others then it will draw more current, which will lead to ignition amplifer failure due to heat. the ecu will only give a low current signal to the amplifer to trigger the coils so cannot see it being the problem.
also check the voltage at the coils with ignition ON they should all be the same, IF you have a low voltage at one coil compared to the others that can also have a effect on current draw that will damage a coil.