UpNcOmiNg! said:
Benji said:
Great to see you got it running! Misfiring on these can be any number of issues. The plug leads are M5 specific and are really expensive for a set. Im sure you could make your own with the right tools and patience, but first make sure that the spark lead is the culprit. Do you have the correct spark plugs? They are quite an unusual type and hard to find - Bosch Y6DC. Open up the distributor cap and check for wear. Clean with emery paper or replace - cap is R650 for Bremi at GW, rotor is about R150.
These motors are also notorious for vacuum leaks which can cause any number of issues. Positive pressure smoke test or soapy bubble test is your friend here. I would probably start with the vacuum system.
Failing that, balance the throttle bodies and make sure each cylinder is seeing equal vacuum at idle (when hot)
Great advice!

raise:
Thanks for the sound advice. The car currently has some NGK R plugs in (not sure how good or bad they are).
What I did to test the problem
With all 6 plug leads in, the car misses
With C4 plug removed, it sounds about the same as all 6 connected.
With C4 and another plug removed, the car dies
I then removed C5 and fitted in the position of C4. Car starts much better and upon start up, still sounds like 5 cylinders.
Doesn't seem like any rotor issues at the coil although, I'll still check anyway.