05 Grand Marquis LS idle issues
 

Hey guys,
Got an 05 grand marquis ls with 117k that suddenly will misfire when its been sitting cold for a day or more. Also it will have a sort of "stumble" to the idle when just sitting in park. The cel was on until I had to replace the battery and it went off. I've got a shot fuse to the OBD so haven't been able to get the codes yet. My dad said he thought it sounded like an O2 sensor. Any input would be greatly appreciated! :)
Also had the plugs replaced last year.
marybeth