How does the jimny control the AFR?

As the title says, how does the 3rd gen with the non-vvt M13A  control the air-fuel ratio? I know it has a lambda sensor on the exhaust manifold and an air temp sensor in the intake tube, but is that it? Is there anything on the throttle body or something of the sort?
I want to make a set of ITBs and knowing how the ECU controls the afr would be really helpful.

As long as the vehicle is equipped with electronic fuel injection and has a lambda sensor in the exhaust, the air fuel ratio is controlled by the injector duty cycle - the percentage of time the injector(s) is/are open compared to the closed time.

The frequency (how many times per second) the injectors are fired will vary with engine rpm, the percentage of the time they are open, along with the fuel pressure will determine how much fuel is injected each time they open.

The lambda sensor will report the unburned oxygen in the exhaust, if there's unburned oxygen it means the mixture is lean, more fuel is needed, increase the "on time" of the injectors.

That's the process in a nutshell, and the answer to the question you've asked, now for the details you didn't ask for.

The throttle body will have a throttle position sensor that tells the ECU how "open" the throttle plate is, it essentially serves two purposes, first is to let the ECU the throttle is closed (idle position) and fully open (WOT) the second is to indicate the rate at which the throttle is being opened (gradual acceleration or you've suddenly stepped on the gas).

Most but not all fuel injected vehicles use a MAF to measure the air flowing into the engine, I'm not certain if the Jimny does, but if it does, then the MAF is also a part of the throttle body, and there will also be some sort of idle speed control, which on the Jimny IS a part of the throttle body.

There are other sensors, MAP (Manifold Absolute Pressure), IAT (Intake Air Temperature), CTS (Coolant Temperature Sensor) that also have an impact, especially on economy and drivability, but, essentially the lambda sensor is what determines the air fuel ratio.

Seriously, if you're going to run ITBs, I think you should be looking at an aftermarket injection system, and that is going to be way beyond a forum discussion.

AFAIK the Jimny relies mainly on MAP. It doesn't have a MAF sensor. The TPS is mainly used to detect sudden changes in throttle position.
If your ITBs are very well matched you may get away with just tapping vacuum off one throttle body for the MAP sensor but a better way is to tap each throttle body through a small bore restrictor then join the four lines together to the map sensor. That way it gets an average of all four intakes. You will also need the TPS on one of the ITBs to stop the ECU from getting upset.
Intake air temp and lambda are used to tweak the fueling depending on ambient conditions.

It's quite a lot of work to add ITBs and you won't get much gain with the standard EU.

wow thanks for all the info, what do you mean i should be looking into an aftermarket injection system?
a kit of itbs for the jimny i was looking at some time ago used gsxr 600 throttle bodies and you could run the stock jimny injectors as long as you didn't want to make over 120 hp, which i don't want to do.
my main concern is if i'd be able to make a kit that still functions without swapping the ecu.
i don't think the jimny has a MAF, at least not my model and engine specifically, because the only sensor between air filter and intake is a little thing that an ecu reader called Air intake Temperature.
also would the MAP sensor be located in the throttle body or the manifold to which the throttle body is attached to?

ITB's or motorcycle carbs 
would need stand alone ecu to make it run correct 
 

would that be necessary even if i found a way to provide the stock ecu with the sensor info it uses as stock?
 

yeah i was thinking of having at least one of every necessary sensor and making a bar to sync all the throttle linkages, also i do it for the sound, not for power.
also i was thinking of getting 4 throttle bodies from suzuki swifts with the m13a, so i could get 4 equal ones

If you're after more sound have you tried drilling a hole in the air box? Making a 60mm hole in my air box has given me lots of induction noise and it has taken almost a second off the 0-60 time. It's a 15 minute modification with no parts needed 

i already have an aftermarket cone filter, and have also made an aluminum intake pipe that connects it to the throttle body, and while the sound has improved, i really long for that throaty sound itbs make