Thanks for the replies.
Theres an independent Mercedes Garage a few miles away that I think I might take it to. See if they can test the fuel system etc.
I dont think I've checked the rotor resistance, although I did take it out and clean it. I will check that. There is also the coil which I havent checked, but will try to measure the resistances. I've not heard of these dying though.
The engine block is the same as the 2l but with a shorter stroke I believe. Most parts are the same.