Thanks everyone for the advice. I'm pretty new to this, so I really appreciate the help.
I didn't use PB Blaster to lubricate, thankfully. I only used it because I had a hunch that some of the rust build up on the A4's shifter was causing the sluggishness. I blasted it, then used a wirebrush to remove some of the rust, but it didnt seem to help much.
What's a good lubricant to use on cables and the A4 shifter?
I will report back tomorrow when I have a chance to try and move the shifter without the cables attached. Thanks!