2000 Corolla: replaced Cat and 02's and still bumpy above 40mph

[sepaul]

So, the car had been driving a bit bumpy at above 60mph so I took it in and they suggested I replace the shocks (80k). That fixed that problem but the check engine light went on about 7k later and indicated an insufficient catalylitic converter. I had that and the o2 detectors replaced and the car basicly vibrates under the hood at over 40mph. I don't feel like it can really handle going much over 55mph.

Basicly I have no clue what is going on and am not sure if a diagnostic (because there is no light on) will do. Also, if they ran a diagnostic when they replaced the cat why did they not catch this problem?

Thanks,
Sean

[Dexterous]

Did you change tires or get new rims in the front?
Are your wheels balanced?
If you're using tire seal (sludge) inside the tires, that can cause imbalance.
Also check engine mounts for wear.

[sepaul]

Good advice. There was gunk from fix-a-flat in the back tire. Also one of the tires was worn much more than the others. I tend to believe that the two events are related.

What a crappy product!

What else can I do to max the performance of this car?
thx,
se

[Dexterous]

I don't know that much, just started working on my car this March.
This site is great for more ino for our cars > http://vamp.darkavers.net