There was only one cat on it when I bought it and that was the only exhaust on the truck I had to build the rest of the system. There's an O2 sensor in the header y pipe no idea off it works or not its a jumbled mess of wires under the hood from the previous owner who was an idiot.

I just pulled the codes again on my older Ford code reader it pulled; 31- EGR valve control sensor fault and 82- air diverted solenoid circuit fault

It's been pulling these same codes ever since I bought the truck almost a year ago

When it first started to act up I pulled over to check and the wires to the O2 sensor were against the headers burning but as far as I could tell it was just the insulation around the group of wires that burned but I'm about to go check