Like Ceenie, I have a series 2 Mi16 which has had the engine out and the head off etc. Was going fine but recently has developed and intermittent miss. Mostly when the engine is hot, worse when pulling at revs below 3000. Above 4000 revs it will pull without miss at full throttle through the revs. At cruising speed on the flat highway it runs smoothly. Thought it might be fuel starvation so changed the fuel filter without effect. This morning I thought I had lost another coil so changed one again without any effect. It seems to be getting worse over time.
I had a similar problem with an early 1.9 405 which I eventually fixed by replacing the ECU. I will try to source a replacement ECU tomorrow but does anyone have any other good ideas?
I guess old electronics are going to be the death of these cars long before they die mechanically. Old capacitors, degraded, cracked plastic insulation etc.