Hello everyone, I need your advise. I'm driving a '97 Honda City, the problem is with the rpm. When I start my engine, the rpm revs to about 1500, then after running for about 20-30 seconds it goes down to 800 when I'm not accelerating, which I think is pretty much normal (or is it?).

Then after driving for about 10 mins. or so, the rpm again revs up to 1500 when on standby. But the weird thing is, when I turn the engine off then on again, the rpm will flicker up and down for about 5 seconds, and then rests at 800.

This happens every time I take my car out. The "check engine light" is off, no warning/alarm lights is on. What could be the cause of this problem? Any help would be very much appreciated. Thanks.