Hi. I'm driving 2004 Optra 1.8LT Automatic. Last time I'm having the problem with fluctuated RPM during cold engine. So I brought the car to the workshop and they clean-up my throttle body (disconnect all parts related including IAC, all socket and tube) and the problem been solved
But I'm having new problem day after that. For the past 7 years, my RPM only at 800 rpm at all conditions (either when I put on gear parking/neutral or stop at traffic light and change it to neutral). But currently, the RPM high up to 2000 rpm during parking/neutral, especially when I change my gear to neutral while engines running/waiting at traffic light, or waiting my sons at his school.
How to solve it? I want it back as before, at 800 RPM. Idle Air Control Valve problem? Throttle position sensor problem?