Is it a 3 door or 5??? The 3 doors have a problen with the sensor that detects the removal of the roof. This automatically lowers the rear window but not sure if it unlocks the doors as well.

had a similar prob just after i bought a 03 td4. i used to get the engine light coming on if i gave it too much right foot when at low revs. turned out it needed a new injector. the fault was that not enough fuel was being delivered by the faulty injector. at the time i was still under waranty...

just remember that all that sludge that your additive has dislodged has to come out somewhere and can block the CAT if your unlucky enough.

Officially you go to your nearest exhaust center and buy a new one or in reality you find a steel bar about 2 feet long and a lump hammer.

Raffles I had the same prob that started six months or so ago. Changed all the same things as you but in the end it turned out to be a blocked CAT. Easy to check - all i did was to disconnect the exhaust at the first flex coupling and took it for a spin. The power improvement was...