As the cat begins to clog as a result of a bad plenum gasket, it continues to clog even after the plenum is fixed. My Ram had the cat replaced twice before I got it and they never addressed the plenum.

Let us know what you find.

 

a cloged cat just makes the engine feal boggy... / lack of flow... it wouldn't cause bucking...

 

The plugs being bad will not make it misfire all the time the reason it does it in o/d with a slight acceleration is because the engine is under a heavy load until it drops a gear, when I had the same problem it ran fine except in o/d, if you make the truck drop a gear does the bucking stop? If so I'd say plugs and from personal experience id stay away from champion plugs in an older truck, they tend to misfire,

 

I respectully disagree.....

 

He said it makes the motor feel "boggy". Exactly the problem, lack of power.

 

I pulled the O2 sensor today. I was surprised, it came out very easily. Zip tied it out of the way, and went for a drive. Check engine light was on, and it did sound quite a bit louder.

It behaved the same on the highway. Drives great in every gear except o/d.

The bucking stops when I give it enough throttle to downshift.

The vehicle currently has copper Champion plugs and basic Duralast wires from Autozone. They have 10,000 miles on them. Would it be worth it to change them out?

 

I was disagreeing with the post "a cloged cat just makes the engine feal boggy... / lack of flow... it wouldn't cause bucking..."

Which is not necessarily the way I would describe it, but seems to fit a clogged cat issue.

 

Champion coppers are fine, and the wires, if still good, should be fine. Routing? Can't remember if you routed per TSB.

If it was same with O2 out, then cat may not be clogged.

 

Although unscrewing the o2 from the pipe can relieve some pressure , it's not an end all be all diagnostic solution if your cat is really clogged/clogging badly. I suggest you have it checked, if for nothing more than to at least eliminate it from the troubleshooting equation.

 

I am going to take it to the mechanic shop that I use. The truck is still driveable, but I don't think misfiring like that can be any good for the motor long-term. I plan on keeping this truck as long as possible, so I want to take care of any major issues.

Thank you very to you guys, for your help. If the mechanic shop doesn't find anything, maybe I'll change the plugs, or at least pull them and make sure they are in good shape, still gapped correctly, ect.