Hows it going folks?

I'm helping a friend out on his 93 Regal custom with 3.1 V6 and automatic. It has a very bad misfire once it warms up. We changed the oil and did plugs and wires hoping to fix it. The car ran well for about 3 minutes into the test ride. It did a quick misfire then ran well again. About 3 minutes later under any kind of load it was back to its old self.

When we pulled back in the driveway I looked under the car trying to source an exhaust leak the car had and noticed the top of the cat was glowing red.

Now I am fairly certain this would be a plugged cat but wanted to verify before I proceeded. What do you guys think?

i had a 94 grand prix that did the same thing. i let it idle on ramps for about 10 mins then shut it off and hammered on the cats with a wooden mallet real good and hard several times then took it out and ran it WOT for a few runs.

although it came back about 2 months later. just a bandaid fix if it works at all.

If the cat is glowing you will need to replace it. I suggest that you purchase a magna flow cat and have it welded on. Much cheaper than the stock cat and it will pass emissions. I don't know if you have tail pipe emissions testing in Point Marion or not. In my county (Snyder) we only have a visual inspection.

Yeah we only have visual in Fayette County.

I appreciate the fast responses.