Thanks Tim.

Ok status update on investigations today. We've found the injector plugs are so worn, assume due to being taken on and off may time due to work undertaken that 3 wont hold and just fall off in your hand! Also 1 of the coil plugs wont hold in place. We figure this in it's own right would easily cause misfire. Pushing everything on as best as possible sees the car rev freely. Have also had the exhaust off and CATs are showing signs of wear but are still all there and flow seems reasonable! Not sure if the back boxes may be an issue and part blocked but figure its best to sort plugs first. So plan is to:

1. Replace the injector plugs.
2. Fit new coil plugs.
3. Will probably De-CAT her while the exhaust is off and save the CATs.

Couple of questions before I start searching the web.:
1. Does anyone know a UK stockist for coil pack plugs, or will I need to source from the U.S.?
2. Anyone know if De-CAT pipes are available for the 260 or we will need to make some up?

Thanks.