I also asked about the possibility of a local tuner being able to track down the problem more easily by experiencing the problem in person, in a controlled environment on the dyno, while watching data in real-time.

Response:
There is near zero chance of a local tuner "tuning", or solving your issue. We will not aid 3rd party tuning at any point.

So I either accept the way it is, or I take a big gamble on paying a local tuner to take a look at it. I don't want to spend a few hundred dollars on little/no improvements. I doubt a local tuner would agree to try fixing it, but only charge me if they can actually solve the problem.