3 yr old always has hand or other objects in mouth!

[Repetitiverobot]

Hi
My 3 yr old ds constantly has his hands, toys, any object he can find in his mouth. I just caught him running his tongue across the radiator!! Bit chews his clothes, toys as well.
I have tried asking him to stop (constantly), just moving his hand away. But it's like its a subconscious bad habit.
He has a red rash around his mouth as he dribbles when he's sucking things.
Will he just grow out of it? How can I discourage it?

I have one of these. He never did it before and for about 2/3 months he chews everything. His clothes mainly till they are soaking. I tell him to stop and he does for a few minutes then hes back at it!

It's so frustrating as he's always got something in his mouth. Hoping he'll grow out of it, but its pretty gross!