It could be as simple as a dirty air filter that is overdue for replacement.
If not Peugeot seem to prefer the correct Bosch plugs to aftermarket replacements. You may have plugs of a different make in the car if it has been serviced in a none Peugeot garage.
If the wrong plugs have been used then the coil pack may be faulty and need replacement.
A diagnostic check might help pinpoint the cause.
Finally I always use decent fuel in our 206cc rather than cheap stuff.
ChicksFan
March 2013