IT only runs on four cylinders on 1994 Mercedes-Benz SL500

Mr car will only run on four cylinders,I have replaced both coils and checked the distributors but It still wont run on all eight cylinders...any advice

Asked by for the 1994 Mercedes-Benz SL500
check the timing,if one of the chain rail breaks the chain will jump a cog on the chain sprocket,this will usually be on the drivers side. you can check by pulling wires on either side.