MY99, full decat, ITG filter, Forge re-circ DV and tek2.5 ecu.
Right, had a MAF fail last month due to a poor idle and occasional 'judder' whilst cruising at around 70 in fifth gear.
Replaced MAF, idle fine.
Engine still 'Judders' at constant throttle, especially around 2500rpm. There is an audible misfire there as well which can clearly be heard as I have a Blitz bb.
I thought spark plugs, was told it could be an air leak. Took it to Keith Price in Abergavenny who inform me that the Lambda sensor is not switching at all, so that may be the problem. So I changed it today and guess what.. there is no difference.
I have now spent almost 300 in labour and parts and it is still misfiring... What I want to know is.. What could be causing it? I am still suspecting a plug, but not sure as when I put my foot down there doesn't seem to be a problem as it pulls like a train and doesn't appear to have lost any performance! Help!!!
Oh and for the record there is no engine light, or any fault codes on the select monitor. Just no movement from the lambda sensor.

Come on guys, surely somebody has at least a clue!!
If it helps at all I have now noticed I am getting a slight 'surge' accompanied by wastegate chatter as I lift off from high boost, is this anything to do with it?
Help me!! Aaarrgghh. Bloody cars :D :D

up in the desparate hope that someone here has a suggestion!

Anyone?