2006 Dodge Caravan P0306 Code

Electrical problem
2006 Dodge Caravan 6 cyl Two Wheel Drive Automatic

I went to my mechanic and my car was diagnose with P0306. i change the spark wires and spark plugs and still showing the code what i should do? Same day he told me about the EGR valve i change it and the problem is gone for the EGR... should i change the ignition coil or the coil have to be set up into the car computer...