Well, as the title says I've managed to fix my apparent misfire and poor idle issues.
Alfa 159 1.9JTDm - 73,000 miles - mix of 'A' roads and Motorway driving - Daily use=25 miles
.......it was that simple, replaced all 4 and the car starts alot better, erratic idle has gone and the lack of response when pressing the accelerator pedal when cold has also gone (Felt like a massive dead spot on the acceleration when cold, just above idle.)
1. Lumpy idle when cold.
2. Dead spot when accelerating away from idle.
3. Varying injector correction values.
None of the above gave any warning lights or other indicators about a glow plug issue.
When I looked at the removed glow plugs they didn't show any signs of failing and the resistance was fine when measured.
It's been a week since I did them and all is well.
Hope this might help someone......or maybe I was just lucky.