'94 940 Turbo, 260k

Here's the problem.
Flushed the tranny (disconnecting the upper radiator line method), it was working fine.
After the flush, it did not want to shift.
Ran it awhile (a few hundred miles)to see if the new fluid would clean things out (Valvoline MaxLife Fluid).
It began to shift hesitantly but did not improve much.
I put a bottle of Auto Rx in it and ran it for maybe 500 miles.
Marked improvement but still not right.

It will shift 1-2 fine, sharp, solid upshift, no apparent slippage.

It will only shift 2-3 if I let up on the gas, otherwise, I can accelerate (slow or fast) to over 65 mph with no upshift. Once I flutter the pedal, it will shift up 2-3-OD very quickly (snap of the fingers) but I do feel a definite 2-3 then 3-OD shift. Once it shifts 2-3, there is no apparent slippage.

3-OD is not a problem, solid, no apparent slippage.

Down shifting is not a problem through all the gears.

I tried manually upshifting with the same results as in automatic mode.

So what do I have? A clogged passage in the valve body? A valve body teardown/cleaning in my immediate future?