'99 406 2Litre Petrol. Idle speed fluctuates +/- 50rpm or so, feels a slight misfiring/miss. Can feel it at speed too, if I keep the throttle absolutely still. Bloke at a garage says it could be a/the coil pack. Is this something I can get hold of & replace. Is there one, or four. Maybe I could just move them along until the issue has gone away ? or is it a case of plug in at dealer or auto electric place & analyse & set up ££££££ ? James