'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