sounds like the bearing to me, I didn't think anything of mine until I had the dealer mecanic take it for a drive, and he pointed it out to me, 20,000 miles later I replaced the tranny, it was cheaper to get a used tranny then to replace the bearing.

If you have a bad bearing in the tranny, it will be obvious. The noise is a kind of growling sound or like rocks in a blender. It is most noticeable at idle with the clutch disengaged. When pressing the clutch pedal to the floor, the noise goes away. Why? because the mainshaft in the tranny stops spinning since the engine and tranny are no longer connected. I wish I had recorded the sound before I repaired it.

The repair is not easy but a patient, semi-skilled amateur can do it. I had help - the Helm pdf manual and honda-tech. If you're lucky to get a used tranny that has good bearings then you don't need to open the tranny case. It's not really too hard to replace the bearings. The hardest part is getting the tranny out of the car!!!

Regardless of how you decide to do it, a transmission or clutch repair on a front wheel drive car is a lot of labor. Well worth it though. My 16 year old VX has a one year old clutch and rebuilt tranny and that only cost me $100 in parts. The bearing itself was about $18.

Spark plugs were zfr5f-11, I changed them to zfr4f-11

I changed out my rims and tires and lost 11lbs per corner for a total of 44lbs. Better acceleration and much easier to turn. Previous combo was 16" tenzo dc-6 and 205/40 falken azenis tires and weighed 35lbs. Vx rims and tires weighs 24lbs.

Compression check was 170-180 on all cylinders.

Should know if any of this helped in a few days as I drive around 100 miles a day.

What was your average freeway speed? 33mpg is way off the mark. There is something more than just heavy tires or a wheel alignment. Unless the big tires is just completely throwing off the odometer, which was already suggested.

Keep in mind the oxygen sensor can go away and cause a loss in MPG without throwing the CEL light.

I also have a California '92 VX, 5 wire sensor and L00 ECU. I'm going to swap in the FED ECU in a week when it gets to my door. I can't think of anything I would need to change but the ECU.

I doubt it's just the rims. My friend had a wheel/tire combo that was around 35-40 lbs on each corner, and after switching to VX wheels, his mpg went up maybe 2.

I think the tranny issue sounds normal. All Hondas I've owned that had from 140-247k on them made more noise in neutral than I thought they should, but they were all fine and I never had one of the trannies go bad on me.

Hopefully your MPG goes up this tank.

Average speed is 55-65 mph.

After putting on VX rims, changing cap and rotor, and switching the spark plugs to the proper zfr4f-11 I am up to 38mpg.

Still need to check the timing, whenever it stops raining.

I am also wondering if my aftermarket rear hatch spoiler is causing some drag. I've attached a pic. It's not a huge one but it looks like its less aerodynamic than the oem one, looks like it would make a decent amount of downforce.

I bet it does add some downforce. While ruining the clean aerodynamic line.
Looks like a wind catcher to me.
I'd sell it and pocket the money. Ebay, probably.

Can you take it off without wrecking stuff and run a tank or two without it? If you do, see if you can find some screws or plugs to fill any holes. Consider rubber "well nuts" from a hardware store's fasteners section.

A Kamm back treatment would continue the roofline rearwards and downwards; that would likely reduce overall drag. This one sticks up; I really think it adds drag rather than reducing it.

However I'm curious what other folks who've taken a course or two in aerodynamics will say.

Checked the o2 sensor voltage from d14 to d16.
As far as i can tell it is the correct l1h1 sensor.

Until it warms up it's completely random, anywhere from -1.9 to +1.9
After it's warm it idles at +0.2 to +0.4
Under normal acceleration it goes from -0.4 to +0.7
When i accelerate and then let off the gas it goes to +1.9
Under hard acceleration it goes to -1.9
At 2k rpm and 60mph it goes between 0 and -0.4
If i let off the gas to the point where i'm losing speed it gets into the 0 to +.02 range

It's never very smooth of a reading, the only thing i can predict is the idle voltage, everything else jumps around alot.

It will go from 0.2 to -0.4 to 0.4 to -0.6 with each refresh of my meter, with as constant of a throttle as i can give it.

Does this seem right? I should be in the positive range at highway speed right?

Here's the spark plugs that were in it, not sure how long they were in.

Nice looking VX. I have a CA VX too. Have you checked the air filter? Could be dirty. Also the plug wires. Good luck on getting into the mid to high 40s.