2007 Campus idle problems

[Bloopeta]

Hi all, newbie and in need of some help :/ Have just bought a 2007 Clio Campus for my partner to start driving, it is idling rough and very low, around 300rpm maybe less, never cuts out though. If you rev it once its past 1000rpm it sounds normal, can drive it fine also once pulled away, its just the idling. Previous owner said have changed plugs, leads, coil pack and were told to change throttle body next. I read codes and brought up p0302, cyliner 2 missfire detected (there was no engine management light present) so I checked the injectors for resistance, they were all equal around 14.2 ohms, but I still swapped 2 and 4 to see if would follow, however after clearing code, and driving for 5 mins it hasnt returned, so may have been an old code. It is now not showing any fault codes. I took the liberty of cleaning throttle body and MAP sensor also. Any help grately appreciated