engine misfire

[blue max]

my engine on the # 3 cylinder displayed a misfire on my diagnostic tool . i replaced the spark plug, all the spark plug wires and both coils, swapped injectors. the engine still idles rough and misfires. what else could cause this problem . i also had a egr flow code readout.

[alloro]

Year?
Engine size?

[blue max]

1998 4.6 liter automatic. i ohmed the old coils and they check good. one of the new coils was out of tolerance. i installed the old coils, replace both forward oxygen sensors and now the truck runs great. the old # 3 spark plug wire checked bad.