please help. idle issues!!! cant catch a break!

ok so i have a carbed 91 mazda b2200 and i have been having really rough idle. ill try my best to describe.
this has only been happening lately. it didnt even happen last winter.

ok so i thought i "fixed" my idle finally down to around 800-900.
itll stay around there for a while til i start driving for more than 10 minutes. then ill start to have the idle problems. when it happens, it drops to 750 first, then drops down to 600-650 and struggle to stay alive but somehow it will stay alive and almost stall but never stalled on me.

i have noticed quite a bit of factors that drop the idle too. when i turn the wheel, when i turn on my lights and when i brake. when i have my lights on and brake, my dash lights dim a bit. not noticeable unless you stare at it and look for the change.

all the things ive done since.
i have replaced my battery and had both my alternator and battery tested. they were good.
i had to wrap one of my taillight wires from an incident i had a while back. but not more than an inch and i wrapped like 3 layers of electrical tape.
i recently ran seafoam through the brake booster vacuum
i have replaced the fuel filter under the hood and the pump under the hood is has been replaced within the past 10k
also replaced my air filter for the carb

i also think i may need a new fan clutch but ive google and nothing said that would affect idle.

please! i really need help!

and i apologize if this is a repost, i searched through here and couldnt find something close to what im experiencing.

please! throw your suggestions at me!

Would like to add everything is pretty much stock performance wise

Take a can of carb cleaner and using the nozzle, while the truck is running, spray around the base of the carburetor and where the intake manifold connects to the head. It may be you have a vacuum leak that shows up after the truck comes off the choke. If the engine stalls, you have found your leak.

so like in between carb and the engine itself?
is there a way you can show a pic of exactly where so i can assure myself of the location?
what if there is a leak there, how do i go about fixing it??

and thank you for your response!

Possible places;

Base of carb where it is mounted to the intake manifold.

Intake manifold where it bolts to the head.

Brake booster line where it connects to the intake manifold.

I don't have pictures, just a memory of where I've found leaks before, due to age and mileage and gaskets or hoses have failed.

If you find the leak, you may be able to tighten the leaking part, but more likely you will have to replace a gasket if it has cracked. How many miles are on the truck?

Ooohh. Ok so pretty much the whole intake check for leaks?

And if its just a gasket or a hose, that shouldn't be too hard to fix/replace. I have about 192k I think. Either that or 182. But still pretty high. Lol

Not hard to.replace at all, in the process if you have the money, if it is a intake leak, id mount a weber on it the nikki at near 200k is probably pushing its life span and starting to fail, from what i understand they are rebuildable but not very tuneable. A weber would be easy especially if replacing the intake manifold gasket.

Hmm. Ive been thinking about getting one for a while. But I don't want to dig into my swap money. Especially if i'm swapping the engine. But if it fails then I'll have no choice to. Lol

i think i may have solved the problem. i followed the brake booster line all the way to the manifold and inspected the hoses. the hose that connected to the manifold was in pretty bad shape so i replaced it with some new hose and on the cold drive home, it didnt act up so hopefully it worked if not then at least i solved part of it. haha

You do know that the small hose near the brake booster has a one-way check valve in it, correct? Or was that not a hose that you replaced?