Sputters at 3000 RPM. ACK! Options

[GTMike]

Hey all,
Not a good night. Motor started sputtering when reaching 3000 rpm. Half-way though a tank of gas. Idles fine. No odd noises. Sputters under acceleration and in park.
Google has not been any help.
Thoughts?
Any help would be greatly appreciated.

[Special_Edy]

You may not need to replace the cat, it can probably be refurbished in this case.

You will need to remove it first. Unbolt the bottom of the converter from the mid pipe at the front of the engine compartment. To seperate the cat from the manifold(3 bolts, 2 nuts) you will probably need to first unbolt the entire assembly from the engine (manifold and cat). Once out of the car the rear bolts on the cat will be easier to access.

Once you have removed the cat, the upper side will be exposed, and most likely be clogged solid. Use a handheld grinder to remove the top fractions of an inch of catalyst honeycomb until the passages are cleared and no longer blocked. Now rinse it out well with water or compressed air to get out all the junk left over from grinding which fell into the honeycomb passeges. Bolt it all back together and enjoy the $500 you just saved yourself. Try not to breathe in the dust created from grinding, there are some heavy metals present in the catalyst which may be harmful to your health.