You start by saying "my mash is never consistent and always lacking in efficiency."
You continue with "So, I first get my hot liquor up to temp (~165-170 F) while meanwhile preparing and grinding the grains. Once the hot liquor is ready, I pour it quickly into the mashtun with the grains, trying my best to pour the water and grains at the same rate to get a good mix. After this transfer, and some gentle mixing with a brew spoon, the temperature of the mash is typically around 152-156 degrees.
I think that those two statements go a long way to explaining the inconsistency.
The "gentle mixing" has already been covered, so I won't repeat that except to say that I agree, and that will help with efficiency and consistency.
The next thing, is that you heat the strike water to 165 - 170, and end up with a mash temp of 152 - 156. That is a very wide range, and will affect consistency.
You should use a strike temp calculator such as comes with Beersmith, or Promash, or http://www.rackers.org/calcs.shtml
. If the calculator doesn't take the thermal mass of the mash tun into consideration, you should pre-heat the mash tun before adding the grain and the water, and you should measure the temperature accurately. Many people, heat the strike water about 10 degrees higher than necessary and pour it into the mash tun (which heats it), and wait for it to cool to the required temperature. Stirring the water helps to cool it quickly. You do have an accurate thermometer don't you?
You didn't mention anything about the mash thickness. I usually use 1 qt water per lb grain. Most people here use more water per lb (about 1.25 - 1.5 qt / lb), but whatever you do, you should be consistent. If you are inconsistent, then your results will also be inconsistent.
As for efficiency, it has already been explained that you should adjust your efficiency to match what you achieve. If you improve your consistency, your efficiency will stabilize and make this easy.
Hope this helps.