You need to check the idle control valve, and the air filter.
It's located on, but right below your thottle body with 3 screws like a sensor. You will be able to find it if you take off your stock/aftermarket Intake.
throttle body
The PVC valve on a 98 Eclipse is located on to or the valve cover. It is connected to the intake with a hose.
The shift solenoid on a 1997 Mitsubishi Eclipse is on the back of the valve body. Removing the transmission pan is required to reach the solenoid.
The EGR Valve on the 1996 Mitsubishi Galant is located underneath the Exhaust Manifold.
Its located on the side of the throttle body. If You'r looking at the engine its on the Right side of TB
It is in the valve cover.
bend valve,burned valve,ring,or a crack
The EGR valve, on your 2005 Mitsubishi, is located beneath the air cleaner. Remove the air cleaner housing. The valve should be visible and labeled.
It is located on the throttle body, it is on the side facing the front of the car between the throttle body and the valve cover
The strainer valve on the Mitsubishi Galant 2004, 2005, 2006 models is located next to the engine manifold.