Trans gone south?

I have a '99 Explorer XLT, OHC, 4WD, A/T. Yesterday, my o/d light started flashing. (the vehicle has always performed well, no problems but an alternator) This morning I took my boy to school. (about 20 miles) No problems, but that o/d light. As soon as I left school, I felt the trans slipping. Within 3 blocks it worsened to lots of rpm and no momentum. I pulled over, tried reverse and all the other gear selections....nothing. I shut it off, waited a few minutes, and tried again. Put it in D, nothing, fiddled with it and finally felt it slip into R. then D for about 2 blocks then it began to slip horribly again. I drove about 2 miles, stopping every few blocks or so, to repeat above procedure. Had towed home. Checked trans fluid, clear, not milky, no noticible burnt odor, though the level seems just a tad high. Haven't observed any oil leaks. Vehicle has 96K. Any ideas or is this one done?

It's a little unusual for a trans to go out all of a sudden like that, especially if the fluid level is good.
Seems like a better than even chance something else is causing it. I really don't have an answer for you, but perhaps the computer has gone haywire, sending bad messages to the transmission. Tow it to the shop and read codes.

There was a TSB on this era transmission where the bracket that holds the EPC solenoid cracks and the EPC solenoid backs out. This required a new bracket and redesigned solenoid. This solenoid regulates pressure so it might cause these problems. EPC is fourth back from the engine of the set of four. Should be obvious if you drop the pan.

Dropped the pan today, wasn't bad at all. Just had to remove Fr. Driveshaft, found front u-joints need replacement. Seemed like a lot of swarfage in the pan..don't know if it's excessive though, as I've never been into an automatic. I did look at the EPC solenoid and bracket as Opera House suggested. The bracket appears intact, though I am getting some movement on the solenoid itself. The other three solenoids are tight. Whattya think?