Had some misfires developing in cyl's. 4, then 1 and 4, and then 1,2 and 4. Replace the coils...and it runs amazing again.
Also, so you know, I low-tech tested the coils by unplugging each one separately and each did cause the idle to turn rough as it should if the coils are OK. But I learned that they can still fail when they are under load.