Had exactly the same problem missing after 4000rpm. Used an old plastic card and smeared a thin (1-2mm thick) layer of gasket silicon around the area of the crack and underneath the coil. Now the car is running 100% It has always been a bit lagy and now the laginess is gone along with the missing. It wasnt really a crack that i found it seemed more like where the plastic was joined together in production but i saw burn marks on the joins as if it was arcing from there. Great Fix!