Drives fine for about a 1/2 hour. Then the tranny starts to slip. Very soon after it won't stay in, or engage in any gear but reverse. Turning off the car then turning it back on "restores" it and all gears shift fine.

This just started yesterday so I don't know for how long the "restoration" lasts since a bee-line was made for home.

I've seen this description elsewhere but never an answer.

***Wild-*** theories: ***
1) I suspect the shift solenoid(s) at the limit of their resistance range since everything is fine for a while until completely hot underhood. Maybe turning off the car allows it to reset for a few minutes?

But my Helms only says "see if it's within range" but doesn't state anywhere what the acceptable resistance range is. Not gonna buy another solenoid assembly just to find out.

2) I've also read that muck eventually gets sucked up into the internal filter, ceasing hydraulic pressure. Turning the car off allows the muck to fall down into the bottom of the case and the car drives normally for a while.

Car has 220,xxx mi.. Purchased at 205,xxx mi; Fluid color previously wasn't awful but I changed the fluid at 210,xxx mi. with Honda ATF because I didn't know the maintenance history. There was a glob I cleaned off the drain plug.

Fluid level then, and now=fine.

Fluid color is good as well.