hello and merry xmas

hi to everybody,i've had my largo for about 4 years,it's a 2ltr highwaystar diesil, i've not had any probs with her except for a blown engine, they are prone to overheating or so i'm told, after the event ofcourse. still such is life.a problem i have at the moment is, it the engine turns slowly then picks up speed be fore it fires,upto 15secs or more, she's had a new battery, hotplug relay to noavaile.i replaced the hotplugs and this seemed to sort it out,it was fireing on the first turn of the key, but now only 3weeks in and it's back to how it was,that is the engine starts off turning slow then picks up speed and fires.any help you can give on the problem i'd be very gratefull.