I'd go to RockAuto or over to Autozone and pick up new wires to be sure. Like it was stated, you are not the first to replace OEM wires with the magnecore set and have problems. I would get the motorcraft wire set from Rock Auto personally, unless you need it same-day, then I would try the Duralast from AutoZone. I have the Duralast from autozone on my 99se, and there is no misfire, but I often wonder if it would run any better with performance wires or not.
