RPM jumps when stop at a light/stop sing.it mostly does it when the a/c is on and the car tries to take off on its own.. I almost rear ended the car in front even doe I had my foot on the break... Can some one HELP me..pleas and thank you..

 

Try checking the throttle body, it may need to be cleaned.

 

Yes. Or idle air control, or an air leak in the intake tract.