1999 Ford f350 super duty 7.3 idels rough
 

On this truck with 7.3 deisel with turbo. The problem is this with the engine at normal temp and at an idel the engine runs rough. When you are driving at normal speed the engine runs ok, but if you slow down between 30-35 the engine starts to run rough. I have changed the fuel filter and air filter. I have also ran injector cleaner thru it a couple times. I pull a 30 ft gooseneck living quarters horse trailer and get 11 mpg. When going up a steep grade and you give it the throttle it blows out black smoke for about 5 min. then it clears up. the turbo was changed 3 years ago. Also it burns about 2 1/2 quarts of oil in 300 miles. Please help me with this problem

i'd bet you have an injector or 3 on the way out and or you have some bad oil seals in on the injectors themselves....

Wonder if your turbo seals are leaking?

my guess would also be injector seals

check injector o-rings

mine kinda does the same as on loosing oil..ive been told by two different people my turbo seals are goin out..so..yea if that helps..

injector o-rings also they make a high oil pressure crossover line that connects the two heads together that is said to smooth out idle and quite the motor down