I had the same happen to my car about 4 weeks ago. Took it to the dealers and they said they could see the misfire but the fault guidance did not find an issue with any component.
So nothing has been done under warranty
...
In my opinion if it's happened once it will happen again, just a matter of time. I had my spark plugs changed back in Sept 2010. Since then I've done around 15K miles without issue... so my initial feeling is that its a coilpack on its way out.
Incidentally, the spark plugs fitted were Denso Iridium Power IK24 and the faults logged were:
3 Faults Found:
001056 - Catalyst System; Bank 1: Efficiency Below Threshold
P0420 - 002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 2
Fault Frequency: 1
Mileage: 86299 km
Time Indication: 0
Date: 2000.00.00
Time: 23:11:57
Freeze Frame:
RPM: 1597 /min
Load: 24.3 %
Speed: 31.0 km/h
Temperature: 87.0°C
Temperature: 30.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 14.097 V
000768 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - Upper Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 2
Fault Frequency: 1
Mileage: 87082 km
Time Indication: 0
Date: 2000.00.00
Time: 09:07:12
Freeze Frame:
RPM: 709 /min
Load: 31.4 %
Speed: 0.0 km/h
Temperature: 89.0°C
Temperature: 51.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 13.843 V
000772 - Cylinder 4: Misfire Detected
P0304 - 001 - Upper Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 2
Fault Frequency: 1
Mileage: 87082 km
Time Indication: 0
Date: 2000.00.00
Time: 09:07:12
Freeze Frame:
RPM: 709 /min
Load: 31.4 %
Speed: 0.0 km/h
Temperature: 89.0°C
Temperature: 51.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 13.843 V
Readiness: 0000 0000
Any ideas what I should try next?
I travel a fair bit and I don't really want to be stranded somewhere with an engine stuttering or running in "safe mode".