I know the AW71 transmissions are very tough, and mine still shifts great through all the gears. But the last couple of days, it's developed a weird problem - when cruising at highway speeds, even if I nudge the gas pedal, it will downshift immediately out of overdrive and I have to take my foot completely off the gas for it to go into OD again. Needless to say, this means a lot of downshifting to maintain highway speeds. Here's what I know:

-flushed last year with Mobil 1, currently full of nice healthy pink fluid.
-OD relay appears to be working normally: I can engage and disengage OD at will, using the shifter button.
-Shifts through all the gears normally and smoothly during regular acceleration. Even fairly smooth during rapid accel/aggressive driving (which I don't do often!)
-throttle cable, cruise control and kickdown cables show no signs of binding, all operate smoothly, they are in exactly the same alignment as they were before this started happening.

So I'm wondering if this is the beginning of the end for this tranny? Or should I try experimenting with the cable adjustment?

Thanks in advance for any ideas.