Just bought a 04 3500 dually wiyh a 112,000 miles. I purchased it on e-bay. When i went to pick it up ,it had white smoke at a idle.Was told that dealer checked out and said it was dirty fuel.6 tanks later still smoking.Had it checked at local garage,#3 injector misfire. Replaced injector ,but now it smokes more than ever. Had test done on all injectors and all was good.I am trying not to take to dealer.Please help.