Well I've plumbed the pcv pipe back in to the top of the induction kit, which made a bit of difference - but I've had to up the idle a bit to help it out because it was seriously low! - worse still in the dark, with the wipers heaters and stereo on.
Gonna change the plugs tomorrow to complete the service, see if that helps things at all - failing that I might go back to the factory airbox with some holes drilled behind the filter 
