I am camping right now and on my way to the campground my duramax started making a really loud rattling sound every so often. sometimes only for a second, sometimes for like 3 or 4 and a lot of smoke would come out of the exaust at the same time. by rattling i mean like extra loud dieseling. it actualy happened a few times in the last week or two put it was always for just a split second. it is a 04 with only about 1500 miles. i am wondering if i am going to make it home from this camping trip. any ideas?