2008 F350 dually 410 gears. Transmission will not downshift with new crom. Will lug engine. Fuel mileage keeps going down every drive cycle. Down to 13 unloaded. I get 12 pulling 15000 raptor at 65 mph stock. The tuner does not stay consistent. I can run stock tune for a couple of days put predator back in it does great then deteriates. There are no factory updates for my ecu ot tcu all have been done.