The biggest fear when it comes to fuel is running lean. Once an air fuel mixture goes a little over 15:1 or so for an N/A motor you end up with a condition where there is too much air and the burn becomes more like an explosion. The higher temps during bad ignition can form hot spots on the head, valves and cylinder walls. The hot spots will then cause pre-ignition (detonation).
A pre-ignition condition robs power and will over stress all moving parts of the motor.
In most cases, a dirty fuel filter will cause the car to loose top end power, but will still deliver nuff fuel to idle like normal.
Usally bucking/bad idle is caused by vacume leaks.
If you have a bad injector, one of your spark plugs will be whiter than the rest, thats the bad injector.