OK, Bo, you're doing good. I see that hose that goes on the big nipple. I looked at that pic of where you think it ends, but I can't see enough to tell where/what it goes to. IT might go to ( guessing here) the EVAP system-the fuel vapors from gas tank, going to a charcoal storage canister. It may even go to the valve cover, and be the fresh air breather hose for the PCV system. For now, try to trace out that hose and figure out where the other end goes to. I'd be surprised if it goes direct to the intake manifold. Try sniffing the open TB end of the hose, do you smell gas vapor?
I can think of a couple tests to do if it remains a mystery of where it goes to. Let's leave it alone for now, we may later remove the TB after the Groove to modify the IAC system, it's not vital to do that yet. I appreciate your photo efforts here, you have probably dome the best job ever of documenting your efforts with pics.
I've done a fair amount of figuring out things like this before, so it's pretty easy for me. But, as you are new to much of this, I think it best to do this one bit at a time. It will be easier for you, less to think/ worry about. We will be more able to avoid problems this way. In the end you will learn a lot from all this!
So, let's concentrate on getting a good Groove done on your Toyota. We can go back into it and go into the more involved stuff later. Now, you see it's not so hard to remove the TB. I'd get a new mounting base gasket for it now. It's good you have a spare complete TB, plus the original.
Basics- Bo, do you have a good idea of the car's fuel economy? Is it running well overall, no problems? How long since you replaced spark plugs, and dist. cap/rotor? How many miles or KM on it? (I forget if you said). Does it have just one Oxygen sensor, has it ever been replaced? Does a check engine light ever come on in the instrument panel? Do you change the oil on schedule? Have you ever smelled the exhaust pipe when engine is hot at idle?
For the Groove to work well, we need a good-running vehicle, w/ no present problems. The Groove won't cure existing problems. If maintenance and "state of tune" are good, we have a good Groove candidate car. The 2 most common things that rob gains from the Groove, are manifold vacuum leaks, and bad/old O2 sensors. That's IF there are no other known issues! Vacuum leaks- look at all hoses that go to intake manifold vacuum, inspect each for cracks, swelling etc. The Groove will turn small leaks into big ones so look at all the vacuum connections. A hand vacuum pump can test hoses/lines that dead end to something operated by vacuum, like the power brake booster, and anything w/ a vacuum diaphragm in it. Start by looking close, and feeling along hoses, if in doubt, replace/fix them!! Very Important to do this, Bo! One good thing for you, is I'm guessing Thailand is a wet climate, so I'd expect fewer dried-out hoses and anything rubber. Corrosion in/on metal is probably the environment issue there. It never snows there, right? (lucky you!
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So, think about these questions, and do please give us pics of when you Groove the TB. Show us the bit angle you use if you can. Don't worry about being perfect, I think your first one would have worked. Check the Groove afterwards w/ a flashlight from in and outside, if it didn't break through before, then you probably won't need epoxy yet. Once you have done the Groove, and checked/fixed vacuum hoses, we can go on, there's a good bag of Tricks to use later. BTW, if you don't use/ need epoxy, I'd advise some light oil to dip the bit in, like power steer. oil, or auto. trans fluid, light oil does a good job to cool/preserve the bits. If you do break thru, but haven't put epoxy yet, you can clean it off w/ brakecleaner spray to remove any oil.
OK enough from me for now, you're doing GREAT, BO!!
Tracy G