Don't forget the cold start test (shown in the powerstroke help videos). I did in my excitement of finding a higher mileage deal but that excitement quickly cooled later when I found out the cost for replacing all 8 injectors (4 were bad). If the mechanic isn't already checking for these you might want to consider:
1. Check FICM voltage (also check battery condition, weak batteries cause FICM failures)
2. Turbo (VGT operation)
3. Engine coolant to oil temp delta (under 15F at 65 mph)
4. Coolant Degas bottle for cracks and pressure test cap (most just replace with new)