FINALLY!!! The truck passed with a new cat, a new rear o2 sensor and a new EGR valve. The EGR was completely blocked with carbon as were some hoses. While it did pass, NOX is still really high at 15mph. It read 1042 with a max allowed of 1058. At 25mph, it read 290 with a max of 918. Any ideas as to why it's so high at 15mph?