1Haha, I know the answer.
For the automatic transmission, the crankshaft and the wheels are connected,
in the transmission, through hydraulic links. At the high speed, however, to
save fuel, the connection is switched to mechanic links. This machenic link
will be released back to hydraulic link when the vehicle slows down.
Sometimes, the release control doesn't work. The engine shuts down as a
result. Exactly the same feelings you mentioned.
Now, comes the million $$$ answer. To fix it, very easy