Fordem will be able to give more info regarding your VIN, but it indicates that your vehicle was made in Japan. And if you have the all electric idle speed solenoid, your engine is from an 89/90 Vitara. In 1991 (at least in the US, and Fordem may have better info on this) the ISC was changed to show the air and coolant pipes.
Is the situation with the idle that you are describing, happening with cold start or after the engine has been started for the day??? Cold start on your engine involves the throttle opener, the mechanical air valve and the ISC. When your engine starts up from cold start, it should rev to about 2000 rpm, and within 5-10 seconds, you should hear a very definitive drop in idle of about 500 rpm, so that your engine is now idling at 1500 rpm. The idle should then slowly drop to factory 800 rpm as the engine warms up. How does your engine start from cold???
When your engine is warmed up and idling, and you use your power windows, what does the idle do? And you advise that your idle changes when you turn the wheel??? Have you checked the routing of the throttle cable??
Have you ever done a compression test on the engine to verify valve timing? If not, you probably should, as everything depends on proper valve timing. I’d also check the spark plugs and make sure that they are gapped to .7mm. It’s better to diagnose problems after you know that the timing is correct.