My chryslers engine shape yellow light is showing and the guy at the dealership said it is poor fuel quality..

ok.. the engine is running fine but that engine shaped light comes on every so often.. i mean the car would drive fine for a long time then that light comes back on and i feel a little bit of a jerk when it switches gears..(note the jerk is seldom) and its strange becuase twice in a while the car turned itself off at a red light then i had to turn it back on again.. does anybody know what is happening? if u quite understand where im coming from.. i dont know what it is?