truck idles fast

[troopv]

I disconnected the battery in my 97 Ford Ranger to replaced the thermostat. Now the truck idles fast.
I can travel down the street at 45 mph and not put my foot on the gas pedal. What should I look for to fix the fast idle?

 

[that09ranger]

what is the engine? and has your check engine light come on?, this happened to my 2.3l i4 and it was a build up of carbon on my Idle Air Control (IAC) valve, i took it in, to a shop they diagnosed and got it cleaned and it worked and my idle when back.

 

[RobWigglezz]

Start it with the IAC unplugged, it should still run but poorly. While it's running, plug it back in. It should smooth out at a low idle. I did this after I cleaned my throttle body because the revs at idle were high and it seemed to reset it.