Freelander 1.8 Petrol '04 Engine Cutting Out?

Hi, recently purchased a Freelander, it was a bit 'jittery' when driving but it was a small air pipe that was pulled off. Since replacing it the car runs very smooth but often when i am slowing down at junctions/red lights etc it cuts out.....do i need to just raise the idle speed a notch or could it be something else?
Cheers