At 3000RPM its going to overheat if you are trying to idle it like that. Thats normal.

You must be getting air into the intake to sustain a 3000 rpm idle. Either close off the throttle plates or check your IAC block off.

Next thing is to look at your timing around the idle bins. IF the timing ramps up to quickly off the idle area, that will cuase the rpm to hang a little. Smooth out the timing ramp and that will make it harder for the idle to climb on its own.