Hear is a easy way to gain a few hp and cure Rough idle. (sometimes)
Inside the Mass air , (between the air filter and the Throttle body, ) there is a small round thing. (less than a dime size) spray this with some brake clean, and the Rough idle goes away and your computer reads more air and gives more fuel. Use Brake clean cause it leaves no residue like carb cleaner and its non flammable.