saturn aura losing power when accelerating.

Hey for the past few days now my saturn aura when accelerating on the gas pedal it tends to jerk and lose power for awhile... as if its losing gas or air i took it to the mechanic he hooked it up on the computer and didnt find anything wrong with my vehicle but this problem continues daily can u please enlighten on whats going on with my vehicle. I asked him about it being th3 oxygen sensor , he then goes on to tell me the engine light is the indicator for a bad oxygen sensor ...help