If you take the air filter box off and open the throttle and look down inside. Check and see with a flashlight if you can see oil coating the bottom of the pan inside. That would mean your plenum is bad. Mine is bad and my truck has no power to drive. I have to fix mine.
plenum repair click here

 

I would be leaning towards a bad cat. The symptoms seem to fit. If you take a rubber hammer and hit your cat can you hear it rattle

 

Thanks guys, I'll be checking when I get to the house

 

Sounds like a clogged cat. But I'd bet the Plenum is shot too if it's not been touched in 16 years...

 

Sometimes they go hand in hand in certain cases

 

......