Unplug the lambda sensor and see if the judder goes as when unplugged the ecu uses its defualt settings rather than the wrong figures from a bust lamda.

Could also be the throttle position sensor going mad.

When the lambda sensor goes you should notice a reduction in fuel economy.

Its worth changing fuel filter as often they get missed by garages. Mine had so much crap oozing out of it and it was the original one, despite a full ford service history. a new filter improved all round performance.