Pajero V20 petrol V6 engine – idle problem

Hello, I have the following problem: My Pajero V20, v6, 3.0 liter petrol, 150 hp, year 96, went out at idle at operating temperature again and again, because the speed was too low (less than 700 rpm). At cold start it ran normal (increased idle – as far as I see it is a cold start controller which raises the speed). But as soon as it had run warm it went out again. When the air conditioning system was switched on it did not, because then the idle speed was automatically increased. But otherwise always. I then increased the idle speed at the adjustment screw of the throttle valve. This was also so wonderful some time – only it was slowed down again from month to month (without which I had changed something) in the idle mode until it went out again. I have now already set the idle speed 2 times at the adjustment screw of the throttle valve higher. And again and again the idle rate is slowed down over time until it goes out. Now I am almost in the final position with the adjustment screw. I have to find the real cause right away. I have read that there is some servo motor. If it is, where exactly does it sit, what does it cost (someone might have needed such a thing?). Or what else could it be for a mistake? -brazilv20