my car is running always in 2,000 rpm when is hot or cold any idea since a week ago .sometimes it will run from 2,000 down to 1,200 and back to 2,000 most of the time when i stop.mode done two year ago acura integra gs 98 ,vtec head,type r piston.no vacuum leaks found yet

 

Check for a failed PCV valve, assuming you're not running a breather filter.
That would create a vacuum leak.

Otherwise, your Idle Air Control Valve may not be sealing well.. and giving the engine more air than the ECU expects.
Ditto the Fast Idle Thermo Valve. It opens and closes based on coolant temp alone.
The IACV is controlled by the ECU.

 

Also wouldn't hurt to do an ECU reset as per Helms/Haynes.

 

Hes right, you could try resetting the ECU by disconnecting the battery for 3 minutes. Your idle valve may be going bad, but check for any physical obstruction. Take the intake pipe off the intake manifold and look for anything odd. It could also need a clean, there is this stuff called "deep creep" thats designed to clean any crap out of it. Do you run a PCV though? This can affect idle.

 

If its ALWAYS been like that you throttle cable may be out of adjustment. When I put my engine back in my car it was too tight and wouldn't go below 2,000 RPM. Just an idea, probably not your problem though.