this sounds like you may have a bad iac [idle air control valve]somtimes you can remove and clean these with carb cleaner and they will work fine,,thoough you may need a new one
The purpose of the Idle Air Control (IAC) valve is to control engine idle speed, while preventing stalls due to changes in engine load. The IAC valve, mounted in the throttle body, controls bypass air around the throttle plate. By moving a conical valve, known as a pintle, in (to decrease air flow) or out (to increase air flow), a controlled amount of air can move around the throttle plate. If RPM is too low, the PCM will retract the AC pintle, resulting in more air being bypassed around the throttle plate to increase RPM. If RPM is too high, the PCM will extend the IAC pintle, allowing less air to be bypassed around the throttle plate, decreasing RPM.The IAC pintle moves in small steps called counts.During idle, the proper position of the IAC pintle is calculated by the PCM based on battery voltage, coolant temperature, engine load, and engine RPM. If the RPM drops below a specified value, and the throttle plate is closed (TP sensor voltage is between 0.20-0.74 volts ), the PCM senses a near stall condition. The PCM will then calculate a new AC pintle position to prevent stalls.If the IAC valve is disconnected and reconnected with the engine running, the idle RPM will be wrong. In this case, the IAC has to be reset.The IAC resets when the key is cycled ON then OFF. When servicing the IAC, it should only be disconnected or connected with the ignition OFF in order to keep from having to reset the IAC.The position of the IAC pintle affects engine start up and the idle characteristics of the vehicle. If the IAC pintle is open fully, too much air will be allowed into the manifold. This results in high idle speed, along with possible hard starting and a lean air/fuel ratio. DTC P0507 may set. If the IAC pintle is stuck closed, too little air will be allowed in the manifold. This results in a low idle speed, along with possible hard starting and a rich air/fuel ratio. DTC P0506 may set. If the IAC pintle is stuck part way open, the idle may be high or low and will not respond to changes in engine load.
INSTALLATION PROCEDURE NOTE: The AC valve may be damaged if installed with the cone (pintle) extended more than 28 mm (1-1/8 in) . Measure the distance that the valve is extended before installing a new valve. The distance from the idle air control valve motor housing to the end of the idle air control valve pintle should be less than 28 mm (1-1/8 in) . Manually compressing the pintle until the extension is less than 28 mm (1-1/8 in).
Locations View (3100 LG8)
that will be fine....before you buy 1..you do need to check for vacuum leaks and also you may want to try cleaning it
sense the cleaning did fix it somewhat,yes,install a new one,,i don't think the air filter is the problem,but if it is dirty,do replace it