[Darren69]

You didnt say if you just have a non standard dash and what it is. The fact that its firing on one at least suggests the crank sensor is working sometimes otherwise it wouldnt fire at all. Does your dash take rpm signal from crank sensor or ignition? Maybe one of the coil sticks has failed. You see where im going with this? Have you tried swapping them over see if it fires on the other cylinder? I still think you're clutching at straws unless you interrogate the ECU.