Do you always run a Top Tier gasoline brand?
Did the blackish smoke occur before or after you added fuel system cleaner? If after, it probably means it's burning off deposits. What fuel additive did you use? I would recommend a bottle of Red Line SI-1 in each of your next few tanks of gas just to make sure things get cleaned out good.
You may also need to remove and clean your ICV, but not sure why tapping the gas once would alleviate the rough idle if that were the cause.