Injectors
Unlike problems caused by a lack of fuel, filtration and lubrication, early LB7 Duramax motors had issues with injectors that had high fuel flow return rates. This was caused by defects in the manufacturing process and caused rough idle, decreased fuel mileage and performance as well as producing smoke at idle. Luckily, if you own a 2001-2003 LB7 Duramax, you might be in luck as the factory issued a recall warranty that covers this issue in all 2001-2003 Duramax's for 200,000 miles or 7 years.
There was a list of Ford and Dodge problems somewhere, but I can't remember if they're on a Word document or in my head. I'll have to sit down in the office one day and hammer out a few page-oooh, did you hear that? Sounded like a built V8 with a GT47 and dual exhaust. What was I saying? Never mind, I have to go check out this truck.