I have tried all of the Puma ignition parts on the Focus and the Focus runs absolutely perfectly, likewise I now have all the perfectly working Focus ignition parts in the Puma. Every part was swapped 1 for 1 and tested before changing the next item.

The only problem I have with checking the wiring to the injectors is the whole lot comes off in a single block, you don't appear to be able to (easily) disconnect one injector on its own. I have a video on my phone illustrating the problem which I'm trying to upload somewhere useful to illustrate the problems.