2003 Other MG Models warming up problems

I have an MG zs 1.8 16v injection. I start it in the morning and it would not idle the pin was up and down, and sounded like it was misfiring, also the orange lengine light came on. I started it this afternoon and it ran like a dream. The problem started 2 weeks ago, its been ok when it is warmed up but misfired once or twice on a 10 mile journey. I have changed the plugs. Checked the air filter, and lubed as many connectors I can find. Starts when cold but isnt idling properly. Any help appreciated.