Tranny?

Thought I already typed one but here goes again.

Lately my 1991 Toyota Corolla with 104000 miles on it has been randomly sluggish when accelerating or at a cruising speed (only those 40mph or less, not on the highway). I thought it was a sign my fuel pump was about to go (my Cavalier acted like that for a couple months before that pump went) but then today I had a more serious surprise!

Driving to a nearby store, my car was very sluggish accelerating. It felt like it was about to stall. I thought I heard a belt lightly squealing and then some odd bubbling. It did it again on the way home.

A short time later, I was driving to the parts store and at 20mph, very close to home, the car bucked and felt like it was going to stall but did not. About a quarter mile later, at 40 mph, I heard a grumbling and all of a sudden the car came to a screeching halt, like the tranny had locked up! The car did not stall, thoguh, it stayed running. I shifted through the gears but the car did not make any shifting noises. I got out and looked for leaks or dislodged car parts, but all looked fine. After sitting for about 3 minutes, I put it back in drive, stomped on the gas a bit, and it went. I pulled over in a nearby parking lot to check again for anything amiss, nothing. The tranny fluid level looked like it might be a tiny bit high, but that was all.

I then drove it home no faster than 20 mph with no incident.

What the heck!

I was thinking maybe my tranny was overheating, but I have no idea. No engine lights came on, gauges all seemed fine so!

Any ideas would be great!

Thanks!