are fine but if its possible and you know someone with another Z swap out the PTU's and see if his works on yours. I really am running out of ideas to tell you and I hate chasing down electrical issues and im sure you are getting frustrated right now like no other. Try to start OHMing, and Volt readings on the electrical connections but in all honesty I hate to tell you it could be possible you are having injector failure which I know you were hoping wasnt it. Injector failure.
I would do what Waggz said and make sure your gap is right on the plugs but be careful also as the Iridiums are brittle. I would try to check plug gap first and make sure all coil packs are firmly pushed down and then if no success I would start cutting down options with a multimeter.
Good luck and keep us updated I'll try and help as much as I am able to but hopefully some of the guys that know alot more then me will be able to give there insight.