freelander 1 td4 engine jerking engine managment light on and cuts out?

hi can any one help me please,I have a 2003 td4 free lander 1.it was going fine until the EML light came on at 70mph.
I found it had a boost leak,so changed 2x intercooler hoses which were slipt.still the engine has lack of power and is jerking.
So found the fuel pump was noisey,changed that still no good.i do not want to keep throwing parts at it,does any body have any ideas?Iam a Mercedes-Benz technican.

Many thanks