Car stopped accelerating past 60 mph and then stopped

Subject vehicle: 2003 Mazda Protege LX, stick shift, 211,000 miles.

Bought this car new and have had it for 13 years now. Car has been great
to me. Just today, I was driving down the highway at around 70 mph and all
of the sudden speed started dropping. I pushed gas pedal and car wouldn't
go over 60 mph. RPMs would not rev up. After about 15 minutes, the engine
shut off. No Check Engine light on at all untl it stopped. I perceived a short-
lived burning smell but no smoke came out of the engine. Water and oils
levels were fine. Car would not start after that. I waited and tried starting it
several times but It didn't start. It cost me $415 (142 miles) to tow the car
back home.

What could be the problem/solution?

Thank you all!