51 plate 206 petrol - air pollution filter?

[Upatdawn]

Our lads 1.4 (?) petrol 206 seems to go into limp mode now and then, his mate says its the air pollution filter and he needs to rag it a bit to blow it through, any ideas?

I know diesels have DPF's but this is a petrol engine

he usually does not many miles at no great speed to and from work

its done about 120k miles

cheers