The rbm gauges come up 1000 it not normal after two minutes the rbm come down 750 i don't know what it is tpc throttle problems
If you can help me ???????????

Welcome to the forums. Is the car you are working on a 2005 Caprice with 6.0?
Is the service or check engine light on?
Would like to know if there are any stored trouble codes, Have the OBD read & post back any codes please.
The IAC (intake air control) controls the idle.
Cleaning the throttle body and installing a new IAC may fix your problem.

Only i change the IAC control
Thank you my bro

When you start the car while the car motor and coolant are cold, is this when it is happening?

If so does it happen again if you cut the car off, then back on after it drops to 750?

If so that would be close to normal, maybe a tad off, but when the car first starts and the motor is cold the fuel system is in open loop, and the car will idle a bit faster till the car warms up and the fuel system enters closed loop.

If this is something that has not always been this way, then as suggested, clean the IAC and put it back in.