I had the same exact problem with my 2002 Monte. Only it was saying that there was a misfire in cylinder 4. I changed all plugs and wires and continued to have the same problem with the power loss and "check engine" light flashing or staying on. I looked online and found that my vehicle fell under a "Policy Adjustment" for a replacement catalytic converter. Which is what my problem was found to be. They replaced my catalytic converter in less than an hour and my Monte is running fine now.
Hope this helps.
Here's a copy of the "Policy Adjustment".
Subject: Special Policy Adjustment - Catalytic Converter #05551 - (09/14/2005)
Models: 2001-02 CHEVROLET IMPALA, MONTE CARLO
2001-02 PONTIAC GRAND PRIX
2001-02 BUICK REGAL
EQUIPPED WITH 3.4L (RPO LA1 - VIN E) OR 3.8L (RPO L36 - VIN K) V6 ENGINE
Some customers of 2001-02 Chevrolet Impala, Monte Carlo; Pontiac Grand Prix; and Buick Regal model vehicles, equipped with a 3.4L (RPO LA1 - VIN E) or 3.8L (RPO L36 - VIN K) V6 engine, may experience a condition where the vehicle exhaust catalytic converter is replaced due to complaints of lack of power or illumination of the Malfunction Indicator Lamp (MIL). This may be due to the front endcone insulation from the catalytic converter breaking away and blocking the front of the first catalyst brick and preventing the free flow of exhaust gas through the converter.
Special Policy Adjustment
This special policy covers the condition described above for a period of 10 years or 120,000 miles (190,000 km), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. The repairs will be made at no charge to the customer.
For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after September 15, 2005 are covered by this special policy and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to September 15, 2005 must be submitted to the Service Contract provider.
Involved are all 2001-02 Chevrolet Impala, Monte Carlo; Pontiac Grand Prix; Buick Regal model vehicles, equipped with a 3.4L (RPO LA1 - VIN E) or 3.8L (RPO L36 - VIN K) V6 engine and built within the following VIN breakpoints:
Parts required to complete this special policy are to be obtained from General Motors Service Parts Operations (GMSPO).
Converter, Catalytic (L36 engine)
Converter, Catalytic (LA1 engine)
Gasket, Catalytic Converter (Converter to I-Pipe, both)
Gasket, Exh Manif Pipe (L36)
Gasket, Exh Manif Pip (LA1)
General Motors will notify customers of this special policy on their vehicles (see copy of typical customer letter included with this bulletin - actual divisional letter may vary slightly).
Catalytic Converter Inspection
Begin the inspection by reviewing the condition described by the customer. Refer to "Description and Operation, " SI document 657895, to help you determine the correct symptom diagnostic procedure when a malfunction exists.
Tuesday, December 2nd, 2008 AT 11:50 AM