The Idle air control is a common problem. Cleaning it doesn't always work, sometimes they are just worn out and need replaced.

The TPS can make it run like crap. It will cause the idle to jump around if it is bad, especially in park at idle. It can make it idle high or low or even fluctuate. You can actually take it out, leave it plugged in, and start the car. Then take a screw driver and turn the little plastic dial inside. Just to test it. When you do this you should be able to raise the idle. Try it out and see how it effects your rough idle.

Personally I don't think it has anything to do with exhaust leaks. But that's just me.