On my way home from work tonight (04 A6 2.7), I was cruising at 65 and as I was coming to my exit ramp it felt like my car tried shifting, but didn't. As I was driving on Rt 43 at 45 mph I was barely hitting 1.7 rpm. Once stopped and at idle I was at 600 rpm. I''ve had CEL P0421 for the passed 6 months and just blown it off because there haven't been any negative effects and I can't afford new Cats. Current test readouts are as follows:

Mode $06 report generated by Torque for Android
================================================

Vehicle VIN: Not present
Vehicle Manufacturer: Unknown
Vehicle Calibration ID: 4Z7907551AA 0010

Unit and scaling information are not supplied with the data from the ECU for this type of vehicle. Consulting the manufacturers service book for this information is recommended.

Test report:
------------------
TID:$01 CID:$05
- Rich to Lean sensor threshold voltage(constant)
Max: 154
Test result value: 218
FAIL
----
TID:$01 CID:$06
- Rich to Lean sensor threshold voltage(constant)
Max: 154
Test result value: 26
PASS
----
TID:$03 CID:$01
- Low sensor Voltage for switch time calculation
Min: 63
Test result value: 128
PASS
----
TID:$03 CID:$04
- Low sensor Voltage for switch time calculation
Min: 63
Test result value: 128
PASS
----
TID:$05 CID:$05
- Rich to Lean sensor switch time(calculated)
Min: 1,638
Test result value: 1,702
PASS
----
TID:$05 CID:$0d
- Rich to Lean sensor switch time(calculated)
Min: 215
Test result value: 1,500
PASS
----
TID:$09 CID:$01
- Time between sensor transitions(calculated)
Min: 165
Test result value: 165
PASS
----
TID:$01 CID:$05
- Rich to Lean sensor threshold voltage(constant)
Max: 154
Test result value: 218
FAIL
----
TID:$01 CID:$06
- Rich to Lean sensor threshold voltage(constant)
Max: 154
Test result value: 26
PASS
----
TID:$03 CID:$01
- Low sensor Voltage for switch time calculation
Min: 63
Test result value: 128
PASS
----
TID:$03 CID:$04
- Low sensor Voltage for switch time calculation
Min: 63
Test result value: 128
PASS
----
TID:$01 CID:$05
- Rich to Lean sensor threshold voltage(constant)
Max: 154
Test result value: 218
FAIL
----
TID:$01 CID:$06
- Rich to Lean sensor threshold voltage(constant)
Max: 154
Test result value: 26
PASS
----
TID:$03 CID:$01
- Low sensor Voltage for switch time calculation
Min: 63
Test result value: 128
PASS
----
TID:$03 CID:$04
- Low sensor Voltage for switch time calculation
Min: 63
Test result value: 128
PASS
----
TID:$05 CID:$05
- Rich to Lean sensor switch time(calculated)
Min: 1,638
Test result value: 1,702
PASS
----
TID:$05 CID:$0d
- Rich to Lean sensor switch time(calculated)
Min: 215
Test result value: 1,500
PASS
----
TID:$09 CID:$01
- Time between sensor transitions(calculated)
Min: 165
Test result value: 165
PASS
----
TID:$01 CID:$05
- Rich to Lean sensor threshold voltage(constant)
Max: 154
Test result value: 218
FAIL
----
TID:$01 CID:$06
- Rich to Lean sensor threshold voltage(constant)
Max: 154
Test result value: 26
PASS
----
TID:$03 CID:$01
- Low sensor Voltage for switch time calculation
Min: 63
Test result value: 128
PASS
----
TID:$03 CID:$04
- Low sensor Voltage for switch time calculation
Min: 63
Test result value: 128
PASS
----
TID:$05 CID:$05
- Rich to Lean sensor switch time(calculated)
Min: 1,638
Test result value: 1,655
PASS
----
TID:$05 CID:$0d
- Rich to Lean sensor switch time(calculated)
Min: 215
Test result value: 1,500
PASS
----
TID:$09 CID:$01
- Time between sensor transitions(calculated)
Min: 165
Test result value: 165
PASS
----

End of report.

Only recent things that have changed was that I replaced my air filter and went to a Valvoline to get my oil done (I know, but my apartment complex wont let me change my oil in their lot).