vito 108cdi (2001) problems

Hi All can anyone help have got a vito 108 cdi the speedo has stopped working have been told it may be the pulse sender is this true, also the rev counter is sometimes eratic and although the engine is not racing the rev counter is at 2000rpm the edc light comes on and loss of power and it splutters and coughs have had the larger off the two pressure switches changed on the common rail any ideas am getting fed up Regards