Thanks for the comments, here is the latest update on the mystery.
We ran a compression test on the engine.
Cylinder 1 = 150psi
Cylinder 2 = 255psi
Cylinder 3 = 245psi
Cylinder 4 = 250psi
So clearly there is an issue with Cylinder 1. So we pull the cylinder head and do some inspection. No indication of any unusual wear or markings. We also used a boriscope to look at the cylinder wall and top of pistons, all of which looked normal.
The gaps on the Intake Valve's for all cylinders was within spec at .09in.
Then we checked the Exhaust valve's, all of which were a bit loose ranging from .05 - .08. We adjusted them to spec at .010in.
We then did another compression test and no change in compression. Cylinder 1 still off.
We reset the CEL and fifteen minutes later it was back on with the same misfire codes, P300, P301, P302, P303, P304, P1399.
I am totally at a loss on how to fix this or what to do next. The car sounds fine and seems to run fine outside of occasional idle vibration.