Have it checked for codes. You could have anything from a TPS to an O2 sensor problem.
Hello, Usually The throttle position sensor controls that. When they go bad, your idle will go up and down like that. I hope this is helpful.
vacumm leak problem.
Cruising down the highway, off idle.
In the event of the lights being left on and the battery dying, the computer "forgets" where to idle. The solution is to hold the gas down while starting the truck and ease off over the period of thirty to sixty seconds. Otherwise a faulty idle air control motor, a throttle position sensor, or clogged fuel filter could cause it to not idle.
The IDLE is controlled by the computer. THERE IS NO ADJUSTMENT.
Idle is automatically set by the computer with the use of an idle motor.
try replacing the idol air control motor.
Your idle air sensor is bad.
Dirt in the carb or carb out of adjustment or both.
The Idle Speed misadjustment, Timeing misadjustment, or bad throttle position sensor. Search one of the 4WD forums like IH8MUD.com or Pirate4x4 for idle surge. check the coolant level.
vacuum leak
Might want to check your idler sensor.