Misfire/poor pick up with light throttle

My focus is giving me problems, particularly first thing in the morning (although the problem never fully disappears) when I pull away it 'kangaroos' on light throttle, if i put my foot down it takes off like a rocket no problem but then if travelling steady at 30 with light throttle the engine seems like it's misfiring and a bit juddery, I disconnected the mass air flow meter and it was fine so thought that was the problem but having fitted a new one the symptoms are still there.
If anyone has any ideas it would be great to hear them.