I have a 2011 LML 134000 miles it has a PPEI 5stage tuner and is deleted. The truck has been great until I too it to our cabin. Coming home there is a few steep down grades and both time when I got to the bottom the truck started stumbling and puffing white smoke it took about 5 min running it to get it to clear out. I had to step on the throttle and raise the rpms up to 2500 before it cleared. I’m new to diesels so any advice would be great!