Do you tend to "overfill" your gas tank and then park the vehicle? Fuel expanding and being forced into the vapour canister, because it has no where else to go, can cause roughness for days.
Filling tank to brim can cause problems @ http://autos.winnipegfreepress.com/i...rticle&id=1186

 

Did you ask the dealer if they had called star center? this way the dealer would have a case file.