Within the last 2 months i have gone though two auto zone thermostats the first thermostat got stuck open and the 2nd one is stuck closed ,so the truck was trying to overheat this 15 degree morning. And my second problem is when its below 40 the trucks idle will staring surging 1100-1500 cold or 1400-2000 when the truck is warmed up when I unplug the tps it will idle at 1100 cold and 3000rpm warm with the idle screw all of the way down, The coolant is full. So what could be the problem. Its a 22re btw

 

hmmm i tired a 160* t stat in my 22re it hated it it would surge like yours soo i went back with a toyota oem 180* one worked great

 

get the cooling system working first, then deal with the idle issue. If the coolant doesn't warm up, the ecu stays in open loop mode and you won't be able to figure out what's wrong with the idle.
once you know with certainty the coolant is at ~180-190 degrees, the idle should be 750. if it's not, come back and let us know and we'll deal with it.

 

^x2..

something similar happened to me the other day.
was up playin in the snow, everything was working fine. then i noticed my truck was surging. and that the motor was running very cold, it was full of coolant but i just couldn't get it warmed up. i also noticed my clutch fan was on all the time, witch I'm assuming was over cooling the coolant. and i noticed once out of the snow, it quit surging. went home and replaced the fan clutch/thermostat, now all is well.

 

i put a fail safe 180 t-stat in, its not over heating but with idle screw closed its idling at 1600 fully warmed up. during summer i had a 160 t-stat and in ran great idled between 750 to 900 but now its gotten colder its not running real good and it was the same thing last years winter when it idled bad.

 

nothing else is holding the throttle open- throttle cable, etc? You haven't done anything to the throttle plate adjuster under the throttle body or the dashpot on the side?

 

i replaced the valve under the throttle body, i don't remember what its called but there is slack in the throttle cable so its not to tight.

 

the maf has also been replaced, should i try replacing the fan clutch next?