HELP, 98' Monte...plugged cat.

[Slinger]

Alright guys need some input on an issue that just happened today. So I go up to watch the ISOC snocross races today, no issues. When I go to leave the car is idling really rough and the car will barely move. Of course its a mad house getting out of the parking lot so im fighting to keep the engine running this whole time while inching out of the parking lot. I can still get up to 70mph for the rest of the drive home but even at highway speeds the tach is all over the place and you can feel a very slight hesitation or almost like a miss every once and a while.
I stop at a gas station half way home to drop my brother off and immediately when I open my door I smell rotten eggs. Now the car won't start after shutting it down for a few minutes. Long story short I finally get it started and limp it home for another hour, but now I am trying to figure out what caused it to happen out of the blue?

The only thing I can think of is a batch of bad gas? I filled up just before I got to the track. Either that or some d'bag poured something in my tank but I'm at a loss. I've never heard of bad gas causing a cat to clog. Engine isn't throwing any codes either.

Do cats just up and fail? Any help will be greatly appreciated. This is my DD and dont feel like driving the truck 30 mins back and forth to work every day this week while the monte is down.

[Shwa Kid]

They can if some particulates come loose and block flow. You can remove the front O2 sensor and see how much pressure the catalytic converter is creating by checking the flow out of that hole relative to the back of the car or the downstream O2 sensor bung. This will throw a code if it already hasn't. I worked on a car of the same platform that had a really flat tire (driven off the rim) and it was running like that when I drove it into the shop, after I fixed the tire it ran fine I doubt they're related... I have a feeling the guy had a loose battery connection and the flapping tire wasn't helping it. Check your battery connection (that's a complete WAG but easy to do). If you do need to replace the cat, they're quite pricey because the pipe is quite long and has some bends in it ($400 here non-OEM), on my buddy's Grand Prix GTP we took the pipe to a muffler shop and had a cheap "performance" one welded in for under $100. While you're at it, it might be worth it to pick up one of these: http://www.zzperformance.com/grand_prix/products1.php?id=504&catid=110 ... I think the Monte's have that U-bend in the downpipe/cat anyways.