While driving on a highway, the car starts bucking and stops

the car bucks and all the lights on the dash go on and the car comes to dead stop. The "check" light stays on. I turn the car off and when I start the car after a minute, it starts up and it is ok. But the "check" light is still on.
My mechanic had it for 3 days and could not find anything wrong. The very next day after I got the car back, the same thing happened above.

Your thoughts please!