ok I have had this problem once before and all I did was turn down the idle via the screw on the TB and that solved the issue.
I start the truck and it idles at around 1500(which it's always done until it warms up). It's winter so I start the truck and go back inside to let it warm up and when I come out it's idleing normal. But now when I go back out side it's still idleing at 1500 and when press the brake the idle drops to 1000 then climbs back up to 1300 and then drops again to 1000 and then back up to 1300.
the idle adjustment screw is screwed in all the way. so I could use some help. The truck's a '94 pickup 4x4 with a 22re and a 5spd
I did use the seach but find what I was looking for.

 

might be a vacuum leak or the oring under the idle adjustment screw is worn.

 

one more thing: it only does it when the truck is warmed up

 

You may have air in your coolent system. The cold idle is controlled with a bi-metal disk and coolent runs against it. The temperature change pushes the pluger closed causing the idle to drop.
Run the engine with the rad cap off and make sure that it is full. Run it like that until the thermostat opens (you see coolent moving). Other then that sounds like a bad vacuum leak.

 

if you have a FSM and an ohm meter, you can check the sensors and see if they are bad.