Study Opening principles. At least get the basic foundation (first 5 moves ) of common openings. The biggest problem with opening tricks is that if you know how to counter them, you will have a decisive advantage.
At the 1400 level, players will seldom do random gambits and openings. The most common you will see from white is Queen or King's gambit, evans ...
First, to address your question, "So if I commit to the KIA with 3.d3 and my opponent plays 3...d6, not allowing any e5 push, I should just open up the position and be left with a slightly worse opening?" - I am tempted to say yes, play something else in this case but in no way you are "worse" after losing a tempo after, say, d2-d3 ...
It's not the KIA at fault (in fact we saw here a color-reversed KID) but you both
lacked when it comes to positional play.
In the end position, Black is far better. He can act the standard queenside pawnroller while you don't have the slightest attacking counterplay, and a horribly bad bishop.
But since so much material has been traded, Black probably didn'...
There's an opening that's called "Ruy López Opening: Morphy Defense, Mackenzie Variation" but it only partially fits your description. It goes like this:
1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.d4
It does have e4 and Bb5, but it has d4 instead of g4.