What kind of plugs did you change to? Get autolite double plat plugs.

99 Blk SE Sport 2.5 CD4E Euro Focus SVT Wheels 5 % tint Mesh Grilles w/indiglo ford KKM intake filter FMS 9mm wires Superchip Signal mirrors Fog lamp mod Dingless A6 sidemarkers Duals SVT springs/struts