Try changing the plug and coil/ignition leads 5 in all. Had same trouble on my old Vauxhall Astra estate and I changed all of the HT leads problem solved. Only a guess mind you.
If you haven't got a workshop manual try you local library, yes that's right library, some loan workshop manuals. If yours isn't amongst them then look one up with electronic or similar type of ignition and the faults solving should be the same or give you ideas on what else to look for. I've been told it's unsual for a module to break down. It's also worth checking out all of the leads on the battery down to the starter solinoid make sure they are firmly attached.
Bob
October 2005