1993 Volvo 850GLT, 4spd Auto

Just looking for general ideas here from those who might be in the know.

About 2 months ago, not seeming to be temperature (weather)related, but if the car sat for 12+hrs - overnight, upon starting and driving, it would take about 1 or 2 minutes before it would shift out of first gear. Sometimes it would work fine right out of the gate, and when it didn't shift, you could slide the shifter down to '3' and it would shift to 3rd (from first), move it back to 'drive' and it would be fine by the time you hit the stopsign to leave the street.

I had the car in for service (Volvo dealer) on some other maintenance and ran the issue by the service advisor, he didn't have an answer off the top of his head - I told him I'd worry about it later, and get the other things I was having done off the list first. At the time, the car seemed fine, it was just a small inconvenience that popped up on occasion. I did go ahead and have and flush/fill done on the tranny while it was there.

Now it seems to be getting progressively worse. My wife used to be able to leave work (after the car sat for 8hrs or so) and it would shift fine EVERY time, right out of the gate. This past week it has been giving her fits when she leaves work. Today after work, it wouldn't shift again, and now when it finally does (or after you force it into 3rd)....it takes about 5 minutes before you ever hit 4th gear (so to do 60 on the highway, she's plowing along at 3500-3700 rpm until the thing FINALLY shifts in 4th).
Checked the fluid idling warm in park - right on the money. No grit, still has a nice redish-pink color. I've seen dirty fluid, so I know what you are talking about.

146K on the odometer, tranny serviced at recommended intervals - not sure if the filter was changed last time. Doesn't shift hard, just doesn't shift at all (until x amount of time/driving has passed.)Doesn't slip at all, when it works, it runs and drives like new. Gear shifter moves fine, not sticking or having to use force to move it.

Thoughts? I REALLY don't want a $1000+ repair - it seems like anytime I've taken any of my previous cars and trucks in for tranny work - it's never pleasant news.

Thanks for any insight, information, a stories of similar issues

Cheers,
Russ