TPS most likely, you should have PF01 (Red) PF09 is 4x4 and black although some of these are also red.

Now the PF01 TPS has a potentiometer with a switch inside so at closed throttle it goes open circuit, it is very important this is set correctly, the ECU looks for this signal to activate it's idle and overrun stratagies. When the throttle begins to open the output will drop from 5V to around 0.5V @ WOT.

A PF09 if you have one isn't correct!

If this isn't set correctly the ECU assumes the driver has taken control (Via the throttle) and so it will make no attempt to control the idle speed and so the idle drops to the point of stalling and the ISCV brings it up again to prevent this.

It's also worth checking the base idle speed as said.

It is adjusted as said but on yours you have to undo a locknut first as 2WD, 4x4 does not have one, be sure this nut is tight when finished as they can fall out if not and are very hard and expensive to replace. You unscrew to raise idle speed and tighten to lower the speed.

Martin