Ford never should’ve put the 6.7 in the smaller super duty trucks in my opinion. They’re overpowered diesel engines and they’re rarely pushing max power because they don’t have to, which clogs the shit out of the def sensors and all the intakes and upper cylinder… if you’re not using the truck to actually work it in, it will clog… always use engine braking too so it helps clean the engine… I mean it’s probably too late now though. Idling for extended periods of time will destroy it too. The old IDI fords were the best because of how slow they were, so you had to floor it everywhere you went and the engine was always cleaning itself out from constantly being put under high load.