My dad has an 00 F250 Extended cab that he says he can be sitting at a red light and it goes to running a little rough and will turn off. Says its hard to start once that happens. He has an SCT tuner and 4" exhaust. Other than that, its pretty much stock. Says it will start blowing greyish smoke and smell like diesel. I havent seen it I am just going off of his word. Any ideas? I will try to fill in as soon as I have more info