[wiswind]

The ignition coils would be a possible issue if you had rough idle....misfire....etc.
As you said that it is running smoothly......I would not look at the ignition coil.

With the vehicle running smoothly......I would see how it does on a couple tanks of fuel with nice easy driving.......
If the fuel economy is OK....then we are pretty much out of the woods.
We might even get lucky and have the idle drop go away once the driveability information is learned by the PCM.....(Let's take all the luck we can get).
But the real key on how things are will be the fuel economy over the next few tanks of gasoline.......