Diesel Bombers - 1999 F350 with turbo No Power

I have a 1999 f350 with turbo. The problem that I'm having is no power. The truck has 191,000 miles on it. I have replaced number 1 and number6 injectors as ford said they were bad. They were replaced around 185,000 miles. have replaced the two blue boots from the tubing to the intake. replaced all gaskets on the exhaust system. The truck has started to smoke alot when I first start it,the color of the smoke is blue that after driving for about a mile or two the smoke is black but not as much. Before you could here the turbo kick in pulling a gooseneck trailer uphill. The turbo does not kickin. It takes longer to pick up speed and does not have the normal take off speed as before. I pull a 35' LQ gooseneck horse trailer and really need help to fine the problem. Yesterday the service light came on and the following codes came up: P0500 and P0720. and P1247. Would any of these codes make the truck run trouble. PLEASE HELP