About The Rpm

I know tis answer has been ask many time but i been trying to look for it but i havent benn able to find it so if anybody can helpme i will apreciate it and the question is

THAT IM HAVING A PROBLEM WITH THE IDLE OR THE RPM
WHEN THE ENGINE GETS HOT THE RPM WONT STOP IT WILL KEEP GOING UP AND DOWN DOES ANYBODY KNOWS HOW TO FIX IT OR HAS ANY IDEA THANKS A LOT BYE

Check the IAC valve. Idle Air Control

i have heard that something like that could mean you have problem with your oxygen sensor and fuel/oxygen ratio