Why would a car with new spark plugs sputter?

Hey Lisa==If it started when the plugs were installed they could be the wrong brand or gap, or the wires and rotor and cap could need replaced. GoodluckJoe A common mistake for this happening after the plugs were installed and the car ran fine beforehand is that the plug wires were put back on the wrong cylinders. If you check all that and it all checks out good, you might have bad gas.