I have several questions about the Ford 7.3L diesel engines. Is the Powerstroke more reliable than the IDI? Are repairs more costly on the Powerstroke, and less expensive on the IDI? Which engine lasts longer? Which one gets the best fuel mileage? What is your experience with the fuel mileage of these two engines? Does a turbo increase fuel mileage, or decrease it? Have any of you gotten over 20 mpg with either engine?