Sounds very much like what is happening to my 2000 reg 75, also failed on the emissions, i have taken the car to a rover specialist (its been there a week now) and they have found the ecu to be faulty they have ordered a new one at cost and as yet they are still waiting for it to arrive, total cost up to yet is a grand total of £488.00. will let you know when i hear anything else.
chrisrc
October 2008