I'd say lower control arms. I'm having the same problem and thats what it seems to be on my end.
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