How often is it recommended to change or clean the EGR filter. I've got 100K on my 6.7 and haven't changed it yet. I'm experiencing "High temps (1090*) when driving at the NOX device according to my EDGE CTS. I've driven Cummins in Trucks for years but this newer "Emissions stuff" is foreign to me. Is there anything else that I should change or check at this mileage?