1993 Mitsubishi Pajero runs rough when cold

hi i have a 1993 pajero 2.5td when you start it from cold it will start but runs very rough with hardly any power and a fair bit of smoke ive done the egr valve was going to give it new filters and a oil change and new plugs to see if that would do it any justice once the bus is warmed up it runs lovely only with a slight judder at low revs ive checked for cracked head and that seems to be fine with no pressure build up or spewing of water or gunk im racking my brains as im to nervous to change my insurance over to it incase it goes pop any answers please