Scanned through asked questions and can't find anything like this!

Wonder if anyone can help before this car getsscrapped, been having this issue for nearly a year in April! Warning light came on 3 days after getting the car , misfire cylinder 4 ,since then its been a journey of new coil packs , new spark plugs , swapping igniter plugs around etc etc and most recently replacing the head gasket because we were told it was slowly leaking and that would explain the misfiring. We thought all was solved until last week the light comes back on shortly after turning on the car , so far I've spent as much on petrol as I have fixing the thing , does anyone have a vague idea of what else could be causing the misfiring problem?

Should also add we had the ECU taken out and there was an error with it but it was fixed , supposedly

Edited by MerlinAE on 19/02/2016 at 14:41