My coils finally failed. Car misfired for about 400miles before I could replace them. The car runs fine now but I had 2 cels. P0301 and 49802 (Coil failure and cat failure). Dealer recommends I replace the spark plugs and cat too. The plugs were changed last March. Is it ncecessary to replace both? The car is running fine now with the new coils. Hate to spend money on a cat and plugs. So far no cels. Might take it in for an emisions test and see if it passes.

 

plugs and coils are usually recommended to change every 25-30k miles. It's best to change at the same time, as one affects the other, which affects emissions...
Test plugs/coils/cat yourself to determine if any further changes are needed

 

If the cat went out it should be covered under the 80,000 mile emissions warranty.
http://www.epa.gov/oms/consumer/warr95fs.txt