The fuel pump filter has been changed .where do I find this high presume o ring .please

I have an 03 pre face lift td4 .I have starting problems as it takes about 4 seconds of constant turning over to catch .I have had the injectors done and glow plugs and cam sensor and low pressure pump .what else can I try

Yes the td4 auto

Hello I have a td4 auto mk1 freelander .not the face lift one . Is there another fuel filter on these other than the one located in the os rear wheel arch .also is it a good idea to use millers injector cleaner