1. Faulty IAC Valve The powertrain control module (PCM) uses the idle air control (IAC) valve to control idle speed. Basically, the IAC allows a certain amount of air to bypass the throttle plate. The extra air enriches the air-fuel mixture during a cold engine start. Set the A/C idle up control screw to 1100-1200 RPM with the A/C on and idling in Park. See if this cures your surging problem. Remove the idle speed adjusting slug and make sure the O-ring is in good condition, replace if needed (this could cause the idle speed to be too high). Follow the instructions in the FSM to adjust the TPS. Redirect the Vents. If the vents are pointed all the way toward one side, move them to face the center of the room. This helps direct the cool air outward into the room. If air conditioner has an oscillating setting, use oscillation only if every fan position serves the general area of the room. If the air is directed toward the back of the The car had rough idling, even engine stalled. So removed the throttle body and cleaned it up. After fixing back the throttle, the idle rpm went up to 2200! Kept the engine idling for more than 10 minutes, removed battery negative twice, but no change! Then took the car for a test ride. Speeded up, pressed hard brake, pressed up, again brake. After a long 4 hand battle with the bottom rad hose I got the tb on and hooked everything up. Started it and was amazed how smooth the idle was and how the idle adjustment screw worked again! So, regular idle adjustment= Fixed. I moved on to the Ac idle up screw device. cleaned it and everything. No fix, rpm stay. Car won't idle normally? Engine surges or revs up at idle? Mine used to as well, until I discovered what the problem was. I replaced multiple parts that m In the factory service manual, in the A/C section, it mentions an "Engine Idle Compensator" and says the following: "this additional aid to prevent stalling during prolong hot weather periods is included with all air-conditioned vehicles. The idle compensator is a thermostatically controlled air bleed which supplies additional air to the idle 6) Reconnect the IAC valve electrical connector. The engine speed will briefly flare and then settle. Compare the idle rpm to the target rpm. If satisfactory proceed to step 7. Otherwise, disconnect the IAC valve electrical connector, adjust screw accordingly, then reconnect connector and recompare. 2. Press the ‘set’ button. The RPM will then rise to 900 RPM. 3. You can then press and hold the ‘accel’ button to increase the RPM above 900RPM 4. You can press and hold the ‘decel’ button to reduce RPM back to 900 RPM. 5. To turn off the feature either: turn off cruise control, step on the brake or clutch. Vehicle RPM Range 900 to Remove the paper clip, start engine and turn up the base idle at the throttle plates using a T20 screwdriver on the curb idle screw next to the throttle cable, maybe 500-600 rpm. Once its done, turn off ign and plug the IAC back in. You could disconnect the battery to erase what it has learned and the IAC fault, then reconnect battery and turn wAiJSw.