Have a Camaro 2001 V6 with 87k miles

Read several posts about misfires and error codes. I have both P0300 and P0420.
The car does not run terribly sluggish but for sure not optimal.
Ended up replacing spark plug and wires which did not help much.
There is a rattling sound from underneath the car every so often. Lately the car also stalls when either slowing down (a few mph) or starting back up again. The car starts up immediately again.
There are a lot of recommendations in other posts but it points towards replacement of the catalytic converter.

Anything else to be done before replacing the catalytic converter?

If replacement:
Appreciate feedback and pointers on where to buy the part(s) and the how to.

Thanks!

 

Well done replace the cat without testing it. Its a simple test if you have a pressure gauge. Most vacuum gauges also measure up to 10 PSI of pressure. Just search youtube on how to test for a plugged cat. I just pull an O2 sensor and put the pressure gauge in there, Disconnect the ignition and spin the engine over. Any more then 1 psi of pressure you know the cat is plugged.

 

Thanks!

Do you have any suggestions where to buy the part and how to replace if needed?
Found plenty of options when searching for parts so recommendations always help for the selection.
Did not find any good how-to when it comes to replacement though.

 

Exhaust work can be easy or tricky depending on the condition (how much rust) and the tools you have. Basically it the same as replacing any piece of the exhaust like a muffler. I have not done a 2001 but I have done a 96 3800 and its just like a pipe with clamps at both ends maybe 2 bolt on the other end and a flange. Normally once you look at them you can see what it will take to replace. I have seen exhausts so rusty I had you replace the whole thing. All the bolts just broke off and pipes so weak they could not handle the force needed to un-install mating parts.A set of touches and a lift sure make exhaust work easy.

 

The car is in great shape and has been in California so rust is not a problem. Will try to get under the car today and see how tricky it would.
Do not have access to a welder so hopefully that is not needed.

 

Hmmm... You can use a Dremel MotoTool or a drill or grinder with cutoff wheel to cut the exhaust. You may want a pipe expander to get the pipe to accept the replacement cat. You must fix the condition that clogged the cat in the first place, might want to pull the injectors for cleaning while you are at it, and check coils. The resistance across the primaries and secondaries need to match or else you will get a misfire, it will be a slight slight lope at first maybe not even . noticeable. But depending on what else is going on with the engine it will get you over time.

Don't cheap out on the replacement cat. Check online or at the GM dealer for pricing on a cat-back. Years ago on my Riviera the local dealer sold me a complete cat-back for not quite twice more than a good cat. Hangers and everything.

 

FYI, a failed cat doesn't mean a plugged cat, but it's bad nonetheless. How long have you been running with a misfire condition? That will trash out a cat in time, if she's running rich. Is that a California license plate I see? If so, you have to get a replacement cat that is California compliant, otherwise you will trip a cat code again due to CA cars having a more stringent emissions monitoring system.