Do I have to replace all 4 coil packs when one.

No. Injectors are replaced in sets. Chrysler already buys their injectors in flow-matched sets so they have extremely little trouble with them. Coils, on the other hand, must be CAPABLE of delivering more spark voltage than is needed to fire the spark across the plug's gap otherwise the potential exists for an intermittent misfire. That capability doesn't change unless they fail, and every coil has a different maximum voltage it can develop. As long as they are still firing their spark plug, there is no need to replace them.