Take the plug wires back to AutoZone and get either AutoLite Professionals or Motorcrafts.
The knocking might be from the ignition misfires which are being caused by cross-coupling of the firing voltages from adjacent plug wires.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
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