A clogged cat was the first thing I thought of when I read this thread. The codes and symptoms (lack of power) are the after effects. That being said, there are two possible reasons why the cat is clogged: 1) The cat is either a bad quality original or poor after-market replacement, or 2) there are other issues with the emissions system. I say that because with all emission components operating properly, the catalytic converter should outlast the vehicle. It is not "normal" for a cat to go bad.

The OP should take his vehicle to a muffler shop and have the exhaust system pressure tested. Too much back pressure means the cat is clogged and should be replaced. After that, an inspection of all emissions related components is warranted.

 

One time my old Jeep Wagoner had a similar problem in the winter and I went through that thing for days and found nothing... mechanic found a nest of come sort in the air filter box AND a some kind of dead animal in my exhaust. Since I live by the woods he said they may have gone in for warmth. Worked fine after removal.

 

I bought the truck used and it had a glasspack on it, but the seller never said anything about a different cat.

Where I live I don't need to pass emissions and don't need a cat to renew it every year. Can I just take it out? Or punch a hole in it for a temp fix? Is it something I can swap out myself without a welder?

Thanks so much for the help guys!

 

Do it right and install the proper emissions equipment. To do otherwise would result in years of throwing money at the truck to fix components and sensors that go bad, plus poor performance and bad mileage.

This isn't the old days where duct tape and chewing gum fixes will work for the long term. Modern vehicles require specific voltages and proper feedback for optimal performance. That is regardless if emissions testing is required where you live.

 

Yes they do. They never fixed the issues with the magnum 318/360s, that steel plenum plate will always be a problem unless copper permatex and the upgraded felpro gasket are used or an aluminum plate is used.


Most people with magnum engines will have a blown plenum gasket and cracked heads between the valve seats, at the same time most people will probably never know it until they've been told and they eventually replace it and see the performance gains that were lost gradually over time. My parents 92 dodge van with 330,000 miles on it runs like a champ and is very strong and it does indeed have a blown plenum gasket and I'd bet the farm that the heads are cracked, very rarely do the cracked heads cause a notable issue unless the motor suffered severe overheating to make the cracks worse.


The biggest problem with those steel plates is that the gasket prefers to stick to the steel plate and pull away from the aluminum plenum and there is no sealant to cushion the push & pull of the gasket.