1990 22RE Fuel Injection adjustment?

Howdy gents, i got a 1990 fuel injected toyota pickup 2X4 22RE and ive been through it a little bit and she runs perty good although the idle seems to be a bit off. sometimes it will idle low and sometimes it will idle higher. sometimes but quite rare it will fluctuate a bit. So i ask you, is there a way to adjust the ration to tune it in better? what is the black turnable knob accessable from the top of the engine? What are the two or three vacuum operated sensors on the top of the valve cover?

 

The plastic "Bolt" adjustment on the top of the intake is the idle adjustment while the A/C is engaged. The base idle adjustment is a screw right by the throttle body. It's down in a little "hole" so you may have to look for it a little. The idle adjustment screw has an o-ring on it that flattens over time and will allow the screw to move in and out and the idle to fluctuate. The lower injector o-ring is the correct size for replacement. If you need any more info, usually Yotatech.com is the place to look for the older pre-Tacoma trucks.