ive got a 05 3500 with 5.9 in and its been blowing black smoke but not all the time just when you step on it or when its loadwed in the lower gears. and have had more oil uses than normal. this is what ive done so far found a bad turbo three months ago . changed oil and filter changed both fuel and air filters also. did cylinder cut out test . it smokes with ever cylinder when i cout it out. did my air to air leak test and ichecked my boots and pipes for holes.where sould i go from here