Rough Idle and poor millage Again!

[BarlowCummins]

I know that there has been alot of threads about poor millage and the rough idle problems and I have spent alot of time reading them. However I feel like I need to ask my own question. Sorry if this is bugs anyone. The last two days my truck has started with a rough idle and after a min or so clears up. I have never had to experience this before and wondering what could it be? Should I take it to the dealer? My millage is dropping again and its starting to bug me now that fuel is $2. 51 a gallon. I have already had the reflash done and never really saw any benefits from it. Any suggestions on what I should do? Thanks Corey