/note to self - no more powerwashing the engine
Haha, and now you have shared the experience to others, thanks!
It does sound like you might want to exchange the ignition coils. Since they have been immersed in water, chances are that they are now corroding. They probably were already, but now it's worsening. The fact that it did run a bit rough initially indicates that, I think. The problem with modern coils is that once the laqueer peels off the iron core of the coil, water is allowed to seep in between the transformer plates. This water will effectively short circuit the coil inductively. As the coil becomes older and rust starts appearing on the plates, the problem worsens to the point where the coil fails even when it's dry.
Chances are that you will experience the problem when the weather has been wet for a few days, then dries up and becomes sunny. This will cause any moisture to condensate in the coil - causing running problems.
/Anders