[wiswind]

Providing that you have solved the vaccum leak, the first thing to try would be the Idle Air Control valve (IAC).
It is mounted on the Upper intake manifold, next to the trottle body.
I would try cleaning it, using a spray lubricant like SeaFoam 'Deep Creep' or even WD-40.
You remove the 2 small bolts that hold the IAC in place, and hold it so that you can spray the lubricant in....and it will run out....so that you will be flushing away the dirt in there.
If this does not work, you may need to replace the IAC.
It is possible for the IAC to be sticking, and not result in a CEL.

The IAC is driven by the PCM and provides a additional way for air to enter the manifold in addition to the throttle plate that your accellerator is controlling.
This is how the PCM controls the engine speed when your foot is not on the accellerator.
It needs to be able to react quickly, or your engine can stumble or stall as you describe.