I have a 2003 Impala 3.8L that has developed a problem with the catalytic converter. The tell-tale signs are all there:

1. Sluggish Acceleration 2. Won't downshift to lower gear to pass or when going uphill (i.e. no power)

I spoke with Chevy Customer Assistance (1-800-630-2438) and they told me that my SPECIFIC car is not covered. Are you kidding me?!?!? This is a very common problem with this car and when I called them they said it's only for specific vehicles. The 2001-2002 impala's are covered, but not mine! There are people with 2004 Impala's that have gotten this covered too (an otherwise $725 repair from the dealer)

My only shot at this is to use the EPA law that was passed that protects consumers against auto defects that affect emissions (which includes the catalytic converter). Here is a link to the document: http://www.epa.gov/otaq/consumer/warr95fs.txt

Here is the letter that was sent out saying it was covered http://i70.photobucket.com/albums/i85/gemstonian/Cat_Letter.jpg

I don't know if this is going to work, I'll come back and update this if it does. I don't have my hopes up. If this is not covered this is my last GM car. They're lucky they're not out of business right now, we (the taxpayers) own most of GM, like over 60%!!! And they have the nerve to deny my claim??!?!?! Seriously?!?

My 2003 Impala had been rock solid up until this month. I got a check engine light about the beginning of the month, and noticed that when i pressed the gas pedal over half way, the RPM's revved up but I was getting no acceleration. I'd have to baby the gas pedal to make the car shift and slowly accelerate. I was panicking thinking the transmission was going out, I already had a 2000 Pontiac Grand Prix lose the O/D cylinder right at 100k. I got the car to AutoZone and had them run a check, and it was reported as Cylinder 2 misfire.

I bought some plugs and wires, and went to my father in law's to get the tuneup done. After the tuneup completed, the issue was still there, and now was getting worse. In addition to pathetic acceleration, just driving the car 10 minutes it was slowly beginning to overheat. I took it to a mechanic my FIL recommended in town, and the guy diagnosed it as a plugged catalytic converter. I didn't even believe him at first, but the explanation that the misfire in cylinder 2 may have allowed non ignited fuel to plug the filter in the converter made sense and i was desperate. He sent me to an exhaust shop that replaced the converter, and exhaust pipe which was almost rusted through, for 185 out the door. Combined with the 150 for plugs/wires, this finally solved the issue.

Im posting this to hopefully save someone else this massive troubleshooting and PITA issue. Since the work has been done, everything has worked great.