Ralentí Corsa 1.6 2002

I have a problem with my corsa. It is a Millenium 1.6 corsa in 2002.
It has been a while since idius revolutions are no longer uniforms.
When you turn on the car, and when it is kept cold it works perfectly (it keeps the revolutions in 900 in idle). But as a couple of kilometers advance (such as 2 or 3km, or being a little hotter), when I squeeze the intoxication and stay neutral the revolutions fall to 200 or 300, and after about 5 seconds, they are normalized again. There are times in fact that the engine goes out, and I have to set it again. This turns without problems, and the car has normal circulation too.
Check Engine turns depletion, the truth is that almost only when I go on a street that has pending, and that is prolonged. After a while the Check Engine turns off again.
I already changed the IAC valve, the oxygen or lamda sensor, the bugies, the benzine filter. A complete affinction was made. But the problem persists. I want to reset the Corsa engine, I think I have done it well (I take out the battery for 5 minutes, with the given contact), but the problem is not solved. I am desperate. Does anyone have any idea what could become?

Cordial greetings,

thank you very much in advance

What codes throw the scanner?

The first thing I would look would be the EGR if it is dirty or if it opens and closes well, because they usually fill with carbon or some oil that always drinks the car and get stuck.

Czech the temperature sensor that bothers a lot in that car, in Toyota the same thing happens is super cheap and you do not lose anything.