2004 Honda City. I have RPM problem in my Honda City IDS

There are a few possibilities. First lwt me know the following;

Did you change the plugs after the problem started?

Does the exhaust look like smoke or smeel like burnt oil?

Were there any repairs or changes done to the car prior to the problem?

Let me know and I will keep this post in my list and get back to you ASAP.

Okay. Sounds like the engine is running rich, too much gasoline, and is fouling the plugs.

The other possibility is oil getting to the plugs, but that is less likely since the exhaust is not smokey.

The next step would be to check the ignition system components>
iF YOU HAVE NOT DONE A TUNE UP IN A WHILE, IT IS NECASSARY BOTH TO ELIMINATE SOURCES FOR THE PROBLEM AND THEY ARE GENERAL MAINTENANCE ITEMS ANYWAY.

You said you checked the coils, so I am assuming it is a coil over plug system. Check the condition of the plug wires. If you have a multimeter you can check the wires for resistance. If the resitance is infinate. Very big, then the wire is bad. The reading should fall into a manufacturer spec. The reading will generallly be in OHMS per FOOT.
Next thing after that would be an air filter. If ti is dirty enough, it can cause a rich running situation.
Also, O2 sensors can go bad and tell the ECU that the car is running lean and the ECU will add extra fuel causing the same problem. An exhaust leak near an O2 sensor will do the same thing.
The next step would be to put the car on an ignition sytem diagnostic.
There are some good sources on this sight for reading the condition of plugs and plyg wires, etc.
Let mne know how things look and the results and we can go from there.