rough idle when warm?

[bluetaxi]

hey, i've recently bought an AUII wagon and have found that it idles rough (drops a cylinder) when it's warmed up. can't really feel it while driving but can when stopped at lights and especially when put in park before tuning off car. it has new plugs, leads and coil pack. does this sound like oxy sensor or injector?

[Beer Baron]

Service your injectors, A slightly dirty injector will be more noticeable at idle.