Never mind. I figured it out.
I created a conditional rule for "Format only cells that contain"
Format only cells with: "Specific Text; Containing; =$C$3 (note, my full data sheet actually has the cell in I3 so that's what I used, I just kept C3 as that was my example)
In the Applies to I set it to : = $E (in Reality, my data set was $D:$F)
This now works as expected.