Originally Posted by 92 Max

Fitz,
At speeds above idle, the VTCs are activated , so if they aren't activating (solenoids open, oil pressure applied to VTCs, they rotate slightly with respect to cams and advance cam timing) it could affect engine. However, at these rpms the O2 sensor controls the air/fuel settings. I'd inspect that next.
http://www.autozone.com/servlet/UiBr...3d801f4e84.jsp