Hi Guys took my D1 on a trip a few days ago got about 550Km on a tank 90L both ways not to bad I thought.

 

Good for you!... Maybe not...
If you have the GEMS ECU it indicated that the upstream O2 sensor(s) are just about gone.
If you have the CUX___(?) ECU... Good for you.
The GEMS uses a Titania O2 sensor that works reversed of a regular O2.
I used to get 700+ Km on GEMS by extending the "I'm running rich" pulse of the O2 sensor and the ECU leaned the mixture... also used water injection at the plenum to make up for the lower power and higher temp.
The engine had a minor rattle before (shells?). Now the rattle is annoying and loud at coasting and idle. I discontinued water injection and O2 tweeking a while ago but before the rattle got worse so the rattle shouldn't be related to the ECU/O2 tweeking. Now I'm happy with 450 as long as the engine still runs.
SD

 

Not sure if my ECU is GEMS how do you tell?

 

If it's always breaking down and costing you $$$ then you have GEMS

 

GEMS were made in 1998 and 1999.
I like the GEMS, I find it easy to alter the imput data.
Look at http://www.gomog.com/allmorgan/GEMS/GEMSbyPoole.pdf for in depth info on GEMS.
If yours is not a GEMS, still read the document.

SD

 

GEMS came out for model year 1996 in North America.