I have an 04 Duramax LLY with 62k. that when i come to a stop in gear (Allison) with my foot on the break it starts to bellow blue smoke and stinks real bad. If i put in neutral the blue smoke goes away but it still stinks. I have changed the fuel filter and tried different fuels and additives to no avail. I then took it to Camp Chevrolet in Spokane,WA. who put it on their machine and said there was nothing wrong.. Not sure what to do next.