occasional misfire

Hi, another problem on my p38 diesel. Occasionally it stutters and drops its revs about 250, you cant make it doit and it only seems to happen at tickover wether you are in park or holding it on the brakes in drive, all spill pipes are new, intank pump/level sender is new, no water in diesel filter which is also new, no bubbles in feed pipe from filter to pump, all help appreciated, it also flashes the injector symbol when you take foot off acelerator pedal regardless of road speed, could they be linked.If my thinking is right will this be the injector with the wire breaking down, as no other injector can be monitered by ecu, many thanks.