2002 Audi A4 3.0 6-Cyl: Check Engine & Coil Packs

138K Miles.
Standard (stick)
I LOVE THIS CAR !
I’ve got a '02 A4 and have replace all of the coil packs (some more than once!) Occasionally it will run rough and the check engine light will flash. When plugged in, the diagnostics point to a mis-fire on a coil pack. In the fall, my mechanic has replaced all the coil packs and now it happened again. This time he replaced coil pack 3 and the plugs. They always check the wires, and they are fine. We are beginning to think its not actually a coil pack, but something else. Any ideas?!?!?!?
-PH