The more suggestions I read here, the more I think that everyone suggesting the cat is correct. I forgot to mention that when I pulled over and put some gas in it yesterday, something did smell hot but I did not feel like crawling under the truck in the slop. I pulled the transmission dipstick and the oil was fine, clean and not hot or smelly. I was watching the rpm's, the coolant temp, etc. but all seemed in order.
I was briefly under it this evening looking around but it was raining so I did not linger. The fuel filter looked relatively clean but I need to look closer and will probably replace it anyway. The truck is titled an 04' but it has fuel return lines to the tank so per my Haynes manual that would be an 03' setup. Being a box truck, I have adequate space to pull the pump if need be. There is also a large device on the left side which I gather is an inertia switch to shut off the fuel in the event of a collision.
The cat looks involved to change out or bypass. The exhaust "T's" and tapers down in an oval shape going right into the cat. I can possible break the pipe loose where it goes into the muffler with my torch rather than cutting it in half and splicing it with a band clamp. That way I could get something into the cat to poke around and suck out the debris with my shop vac. Then if that cures it, I could replace it, heh heh.
I also need to ask around to see if someone I know has something to read the codes before I take it out on the road again. Or, maybe pick one up for myself. I never felt that I had enough use for one.
