Two idle problems- idling high, and almost stalling

What is your question?

when i start my car it will either run fine, idle high, or almost stale. -The idling high problem will also happen if i get on the gas or put it in neutral and rev the engine. it will slowly go back to normal or if i rev the engine a lot it will go back to normal faster. - the almost stalling problem happens when i start the engine and when i come to stops