Sporadic lost of boost under moderate boost conditions

[250Kandcounting]

Greetings all, and thanks in advance for whatever words of wisdom you may have.

My '95 Aero with TCS is having an annoying issue. Under conditions of moderate boost, where the needle is typically at the white/yellow border, the boost will just seem to fade and the car will go sluggish. If I back off the accelerator then depress it again to the same levle, the boost is back. Under heavy acceleration, it is fine. It is very noticable, for example, going up a hill, and the car didn't used to do that.

I looked at lthe vacuum hoses, and the one to the turbo bypass valve was split and crumbly, so I replaced it. The rest of them seem fine.

The check engine light is not currently on, but has been on in the past. The codes it claims are 2 and 6 (but I assume that if the light is not on, the codes are not relevant and the problem detected has gone away?). The mileage is just as it always was, about 24mpg back and forth to work.

Any thoughts on what this could be or ideas for diagnosis?

Thank you
Dave