Well after all the efforts from every one I think I have rectified thr slight miss. As with a lot of these sorts of problem it turned out to be a simple fix.

After I read Bee Utey's post on leads and EMF etc. I rechecked my distributor and module istallation. I had installed the Bosch module on the left hand guard and then run the trigger wires back to the dizzy through some plastic spiwrap type insulation and cable tied it to the metal altenator adjuster. My mistake was that I had it on the rear of the bracket and it turned out to be too close to the plug and coil leads. It was picking up EMF from these and corrupting the trigger pulse to the ignition module. All I did was move the trigger wire to the front of the bracket so that it acts as a sheild and Bingo problem solved.

I think what I will do now is get some sheilded cable and redo the trigger leads.





So thanks for all your help. Hopefully we have all learned something.
Mal