kennard went through this misfire adventure for a couple of months. His got so bad that the plug insulators were cracking after a few days of driving.
Turns out it was the combination of plugs & wires - even though he had replaced both sets a couple of times.
You've gotta get the Motorcraft plugs & Motorcraft or Autolite Pro-fit wires to make some Zetec engines run properly. I don't know why, that's just the way it is.
Return the Bosch wires & upgrade - while you're there, get a fresh set of plugs. Replace everything at one time and enjoy.
