So after being told by most people here and a few other places about the intake manifold being my problem and this and that... I finally went to my hometown mechanic who told me it was the cat. No acceleration, bogs down, tranny having problems shifting... So I spent the 400 on a new OEM installed cat and BAM problem fixed. Perfect shifting and great accelleration. I guess a major problem with GMs is a coolant leak that leaks into the manifold and the coolant then crystallizes on the cat's screen clogging it faster than normal.

Great Job GM.

So anyway, just a word of advice, consider the cat if you're having issues similar to mine.

On a side note, I take back everything I've ever said about Flow40's not being loud. I guess I had a semi clogged cat when they were installed because now my SS is stupid loud, and I love it.

 

Not sure your cat failed due to coolant. When the intake gaskets leak, typically the coolant mixes in the oil or is blown out as vapor out the exhaust.

Your signature indicates you have a '01 SS. GM had a large bad batch of cats on '00-'01's. They extended a warranty plan to 10 years or 1xx,000 miles as a result. If you still had the original cat, your root cause for performance was probably linked with that TSB.

Either way, good your problem has been resolved.

 

Warranty?? I take it that it probably just expired last year then? My car just hit 182k and its still going pretty strong minus some clicking and tranny whine when i hit it hard. The PO never said he replaced the cat so maybe it is original, though I would think that it would have to be replaced at least once before 182k miles.

I am extremely pleased that I have my MC back to normal again. I can't tell you how frustrating it is to not be able to make it up hills at speed. I was afraid it was going to be worse than just the cat to make it running.

 

Pretty much, as I understand the extension of the warranty from that TSB is expired (but there may still be people with failed cats affected by that manufacturer defect listed in the TSB). Handy to have for reference.

And you would be surprised how long a factory cat can last. I know two Grand Prixs ('97 and '98) over 150K on each, factory cat. No performance or emissions problems. My '94 Grand Am I use as a "daily driver", 210K, factory cat still (not the factory muffler, that rotted away long ago). And that car runs as good as the day I bought it.

 

Im wondering if your symptoms tie into mine... I have an 06 3.5 and have been recently experiencing some minor troubles. Especially in shifting gears, as i accelerate and the monte goes to shift i feel it shift and the instantly after i feel it sort of jerk back. I hit a certain RPM around 2k or 3k i think and instead of accelerating it gets stuck at that RPM and sits there untill i push the pedal down further and then the car will shoot forward as though i almost floored it. Though i have no problem controling these symptoms even in the NY traffic.

If my symptoms are similar to yours then maybe it is my catalytic converter that has gone bad.

 

That does sound like a clogging cat. When mine was clogged trying to go up a hill it wouldn't want to go until I let off the gas and pushed down again.