Replaced plugs wires and engine runs worse. Could the coil pack be going out?

That's certainly possible!... However I think you should re-check the plug wire firing order to be sure there're not crossed... Also easy to break//crack the 'white porcelain' spark plug insulator when tightening... OEM coil is numbered for cylinder id.. Passenger side cylinders are 1--2--3.... Drivers side cylinders are 4--5--6.... Front to back... See below: ENGINE: . 1--2--3 > passenger side || < < front of engine . 4--5--6 > drivers side COIL PACK: back 3-o---o-4 2-o---o-6 1-o---o-5 front