Ok guys, first off, new to a Cummins. Bought a 2009 3/4 ton 50,000 miles 4x4. Fuel mileage is on 11.5 mpg. Called the dealer and they're gonna clean egr and cooler they said. Would a dirty egr cause this horrible of mileage. Truck is bone stock. Anyone got any ideas of anything else they can check, ecm updates etc???? Other than the mpg, the truck runs good. No smoke or anything like that.