This is called stalling. It occurs when the gear-shift doesn't change gears correctly because of changing on a bump (train-tracks).
vehicle is still in gear, step on clutch
An automatic gear would stick in 1st if there is an obstruction. Gears can sometimes break off and cause motion to stop entirely.
There are several things that can cause your automatic transmission not to go into first gear. The most common cause is low transmission fluid.
if the kickstand is down, the safety switch will kill motor. or it may be defected.
I have a 95 Lumina 3.1 and it would cut out of gear when I would stop, it turned out to be the sprag gear in the transmission. $$$$
Coasting requires you to put the gear into neutral and let the car freewheel down the hill. If you came to a bend on the hill and someone was speeding up the hill, you may not have enough time to react and slam on the brakes, or slow down. When you aren't in gear, you have less control of your car, as opposed to if you was in gear. E.g. If you were in gear and slammed on the brakes, your car would stall, jerk you forward and stop, however because you aren't in gear, your car won't stop rolling.(It's why you can push your car when it's out of gear, but you can't push it when it's in gear).
The cause of a Xbox 360 to stop playing sounds when a DVD is in it could be that the sound is turned down or has been muted.
You need a tune-up
Check the fluid level. If it is full you have a more serious problem.
check fluid level
I have the same issue on my '93. From what I've researched, the most common cause is bad motor and/or tranny mounts. Also, some people have said that the idle needed to be turned up a little. If you're at a stop light with the car in gear, try giving it a little gas while holding down on the brake FIRMLY. Does the car stop vibrating?
Worn out gear. You need a mechanic !!!!!!!!!!!!!!