This truck does eat oil. I assumed that it just needed a ring job, but it lends credence to the Plenum problem. (But, there are so many things about the Plenum problem that don't relate.)

 

What brand crank sensor?

Edit: Burning oil? Yeah, that's a pretty good sign the plenum is blown. Wonder if its just your cat clogging up? Could try pulling the front O2 out of the exhaust completely, and see if it runs any better.

 

The crank sensor was from AutoZone, but I don't remember the brand.

What would clog the cat? Oil, dirt, or sludge of the two?

 

I crawled under the truck yesterday to identify the O2 Sensor nearest to the cat. What I found was that I don't have a cat. (This is a Chassis Cab, which has been elongated.) There is a section of exhaust that has been welded in to allow for the longer chassis.

There is a carbon canister, under the passengers door attached to the iron strut, but it doesn't appear to be connected nor working properly.

With that, I could only find one O2 sensor. Today, I'm going to remove it, and try driving without it to see what happens.

 

Drove it without the O2 Sensor inserted in the hole. (Wires still connected.) It had the same problems.

I stuck the magnet through the butterflies to check for a steel plenum, and the magnet did stick. So, I'm assuming that I still have a plenum problem.

 

See any oil down in there? has the plenum ever been addressed?