Two days ago my car had a couple of misfires. Checked it and the code was P0303. on 2004 Ford Taurus

After getting code it said it misfired on 3rd cylinder. But while I drove home the day that this happened, the engine light came on, that's how I got the code. I had new motorcraft plugs and wires installed. Now the car is idling too fast, then drops down and goes up too high again. Can anyone help me?

2 answers
Reset computer and drive it 3 miles..
Vacuum leaks are common on this engine! That will cause the rolling or fluctuating idle.