annoying rattle

hello everyone ive got a rattle ont td5 thats got me stumped it revs lovely when stood still, no rattles at all apart from the diesel rattle but when its going down motorway its quite loud now ive heard about dmf going wrong but its only done 85 thou and ive also heard about the injectors going south,i have ordered a new loom for injectors because there was a bit of oil in the multi plug on the rocker cover ,but ive no idea where to go with this if you change gear without accelerating the knocking noise is hardly there but as soon as you boot it its quite load,as it doesnt do this when changing gears with no acceleration ive ruled out big end bearings i may be wrong thou as ive said dont know where to go with this next cheers