95 Lumina Transmission - Overdrive bucking at around 80km/hr

I've looked at all the possible solutions your website has offered (Awesome site by the way!) And have a suspiscion that you're going to point me at the TCC solenoid, but here are the symptoms and what I've done.
No problems cruising at highway speeds except when the car gets down to the point where it has to downshift out of overdrive under low acceleration. Under this condition the car acts like a bucking horse for about 4 - 6 seconds until the downshift happens, usually after I give it more gas to increase the acceleration. If I step on the gas to downshift intentionally with more acceleration than normal, there is a very slight shudder as it downshifts, but no bucking. All other functioning is normal. Help is humbly accepted. Happy New Year.

:D