Will putting Fuel Additive in gas tank stop sputter ing and backfiring?

Well since your are saying its sputtering & backfiring, below are some list of items you may want to check.

* Check to see if you are using the right fuel type in your car, using low octane fuel in a car requiring high octane will cause premature detonation similar to back-firing

* Check your timing and if any of the spark plug wires are crossed if any one worked on the ignition system lately The above items are pretty easy to check.

Sputtering will also occur if any one your cylinders are not firing. Usually occurs when you first take off and in overdrive. But once you are up to speed it does not happen anymore.