Thanks for your reply - getting the fuel pressure checked tomorrow as I have a possible theory.....

Out of interest, is there a min/max number of times that Co screw will turn before reaching a stopper?

I have logged all changes to return if necessary but the Co screw seemed to just turn and turn. It went 4 full revolutions until it reached 3.5% Co, but didnt go below that. Doesnt seem right to be so have returned as it was.

Is there an electrical test you can do on the map sensor - I would like to rule that out.

Huw