2005 Chevy Malibu Engine Runs on only 2 Cylinders

I have a 2005 Malibu Classic. It ran okay yesterday, then today it started running really rough, with no power like it was missing. The check engine light came on and I drove to AutoZone and they did a check of the code and it said "Multiple misfires on cylinders". I pulled the coil pack and changed the spark plugs. Then with a spark tester, I checked for spark and the 2 center lines don't get spark. The Haynes Manual said that there are 2 coils, one for plugs 1 & 4 and 1 for plugs 2 & 3. So I have narrowed it down that the coil on 2 & 3 is not giving spark to the plugs. But would it definitely be to replace the coil pack? There is also a control module on top of the coil pack that the Haynes Book says send a signal to the coils, and also would the computer send a signal to the module? Any help would be much appreciated. If I change the coil pack, what if that's not it. The coil pack is around $125.00 and the control module is the same. How can I test and narrow it down further?

Thanks,

Joe