my 97 civic ex engine... keep on shutting off

when i turn the keys to start the car.... it start then.. in a couple of second it shut off.....
it feels like therez not enough electricity to keep the car from runin .... or like no gas is goin into the engine so it shut off.......

i have no clue on whatz goin on.... because when i bring it to the shop... it work normal.... it only happend some time......
the mechanic suggest i might need new spark plugs???? if any one can help me on tellin me watz wrong wit my car ... it will be great help....