Low MPG, looking to improve, help?

[TwoGlassEyes]

Brand new to the forum, hi everyone.

Here's my problem, followed by what I've tried so far:

I'm getting 37 mpg in town, 34 or less on the highway in my 1994 Civic VX. In town, the mpg stay the same whether I run AC or not (and I live in Southern Arizona so the AC is on a lot).

Starting from a stop always seems a tad rough; very easy to stall if you've never driven it before (I've seen a couple of people do it who should know better, if that makes any sense).

Especially when the AC is on, the car gets a little jerky (sort of like it might stall) when I try to maintain speed, especially at higher speeds. I feel like I have to be very slowly accelerating all the time to avoid this, then let the clutch out to drop speed before repeating the cycle. The ride is still smooth; I only notice because I drive it all the time and can feel it.

I replaced the O2 sensor about a year ago to pass emissions, but did not see an improvement in FE (though it made a dramatic change to my emissions).

I replaced the spark plugs, spark plug wires, cap and rotor; so far, no noticeable difference in FE.

The tires are NOT what I want, but I can't convince my wife to let me swap them out since they're still in good working order. They're 175/70/13; I know it's supposed to be 165/70/13. I'm sure this contributes to the low FE, I just don't know how much.

Also, I don't know when the car goes to lean burn mode, if at all; I'm not sure what indicators I should look for to see if this is happening, etc. This is my first Honda, my first VX, I've had it for about 2 years now and haven't been able to look into this issue when I've wanted to (my wife's Corolla takes up most of my limited garage time).

Thanks for reading. Any suggestions are welcome.