i have a 93 gmc 3500 with 6.5 turbo diesel and it has around 150,000 miles on it. and when i start it up in the morning it starts up but chugs and blows blueish white smoke and will then if i hit the throttle it still chugs and blows smoke, then evens out after a few minutes. Would injectors be the problem? or what are your guys opinions. any input would be great. then after its warmed up and i start it up it doesnt do it, its only when its been sitting over night.