2004 Ranger, v6, 3.0

Quickly; 2 months ago check engine light, sputtering, cylinder #4 misfire. replaced plugs. last fri, sputtering, code again #4 misfire. replaced wires. Monday morning check engine light comes on again. replace coil in my work parking lot. No change. Towed home. Borrowed code reader and just in case changed oil and filter. No codes now but loud knocking and no get up and go. May code if I run it longer but the knocking bothers me.

Anyone with any idea? I'm hoping to run a compression test tonight and if that's good move on to O2 sensors.