Mitsubishi Repair: Surging idle, mass air flow sensor, mass air flow

Question
I have a 1995, Mitsubishi, Galant S, 2.4L, Manuel, my car recently started to have a very strand idle, begining when i start the vehicle it revs up to 2500 to 3000 RPM then drops to 1300 RPM and then to 1800 RPM and then back to 1300 RPM and repeating its self only at idle, but once there is a load on the car such as driving it goes away. i have changed the MASS Air Flow sensor and does not fix it, but if i was to leave that sensor unplugged it seems to still ahve a rough idle but not as bad. ive also changed the PCV Valve. I was wondering what would cause this, i would like to have the car up and running as soon as possible due to its my only way of working. Thank you

Answer
Shawn,
A common cause of idle surge is a malfunctioning idle speed controller (ISC) also referred to as an idle air control (IAC).  This is a small stepper motor connected to the throttle body that regulates the idle speed when the engine has reached normal operating temperature.  Check and replace this component if it has gone bad.
Good luck!