Basically, the apdc feels a tad light and unstable...I am just trying to get some more stability and maybe a little more pop on my serves...
In general, when you're looking for stability, the best place to add is at 3 and 9 o'clock and work from there. Whether you should also add counterweight in the handle will depend on what you're more sensitive to. Some people are more sensitive to changes in static weight, in which case they should not add to the handle. Others are much more sensitive to changes in balance and swingweight, but less so to static weight. In that case, adding weight in the handle will help make the racquet seem less different.
In your case I'd suggest a two part process. You can start by adding some weight at 3 and 9, and then play with it. If you like it great. If you don't like the feel that gives you, then try adding a little weight under the handle and see if that helps.
N.B.: The problem with adding weight at the throat is that it doesn't have as strong an effect on stability as putting it at 3 and 9. Even if you end up with the same balance and swingweight, the racquet won't be as resistant to twisting as it would if you do the 3/9 thing. So based on your stated goal of stability, I think you'll be happier, and feel more of a difference from less actual weight added, with the method mentioned above.