Use MAF cleaner on your MAF and throttle body cleaner on your throttle body. I've done both within the last two weeks. I had a touch of a rough idle and decreasing mpg's. Cleaning the MAF didn't do anything for either but cleaning the throttle body did make it idle smoother. MPG's are TBD at the moment since i've only driven it 1/4 tank so far.

My throttle body wasn't that bad on top but I took it off to make it easier to clean. Good thing I did as the underside and edges of the butterfly were pretty dirty.