Plugged cat was my problem (pass side). Cleaned out the debris & tried my best to flush anything out of the rear cat. Cleared codes (PO301,302,303) via Autozone and engine light did not return after a 1 hour highway drive. Will monitor. Nothing to indicate a misfire during the drive (I was careful when I removed the wires, used a 17mm open-end wrench after dismounting the coils). The misfire codes only appeared with the first power loss which, in retrospect, was probably the initial demise of the forward cat.
Thank you again arkie.

Sorry CharH, didn't mean to make you defensive. I always try to remember that 'it's your car and your money' so you get to make the final decision.:D

No apology needed since I wasn't defensive.
But I was working on a customer's car, not my own.