SOLID, not flashing, S-Light

[Shrewz92]

91 Accord LX, 179K miles, AT, F22-A1, fresh DEXRON III AT fluid after radiator change in March 05.

For several days, Car starts with 'S' light 'on', and feels like NO pull, no oomph. After about 500 ft, light goes off, and real-power returns. It's like nothing's wrong. I have started the car up again, 's' light is on after all the other idiot lights go off. Usually, it has been going dark after 500 ft or so of driving and transmission cycling as normal, through its shift pattern.

Now, after pulling onto Interstate today, the 's' light was on and off intermittently, for various lengths of time: Accord was down-shifting to 3rd when the light was on, shift up to 4th when it went off. After approx 7 min drive time, at 65mph, light went off and no 's'-light issues for remainder of 17 mile trip home. I've been reading about 'flashing' S-lights in this forum, but not solid-on ones.

I'm thinking that both problems (the s-light on at start-up and today's cycling between D3 & D4) are related. Would this have to do with which of the two: the shift-solenoids or the torque-lock solenoids? Since neither the 'S' light nor the D4 light isn't flashing when jumped at the service terminal, the VSS may not be culprit here, as other threads have diagnosed for others. Speedo & Cruise both work. From what I've read here, I would imagine that the VSS problems keep the D4 light flashing when jumped at the service terminal.