Not the coils the PTU in Z32s. I had to replace mine. http://forums.nicoclub.com/tip-for-ptu-problems-t276337.html
http://tech.aus300zx.com/ignition/ignition.htm
Igniter should be a separate unit consisting of transistors/diodes. they are on the back of the rocker cover on rb26s - not sure where located on r34gtt. They are also referred to as a Power Transistor Unit
If the only thing moved/disconnected was coil packs to change plugs then it is typically coils. if not, Check leads next, if not then igniter might have a fault.
Just checking with this question, did you change the timing belt/move sensor to do so?