Every time you have some weather when it´s rain some bit, cloudes, you can´t get over 5500, every time the engine dies, egt goes down. When you dive, it comes back. This happens even when you are not close to cloudes.I hate this, happend on the C340, too.

try leaning your mixture

Hello,Im flyin fs now 15 Years and i know that:- ihave to lean- where the mixture lever isI'm flyin A2A Piston driven aircrafts, you bet i know what leaning is.In fact, the engine dies, you may move your mixture lever, this doesn't lead to anything positive. This happens when you see some grey clouds. Yes, icing conditions have to be respected, but with this behaviour, you may use this aircraft only in clear sky conditions on a summerday.

It might be the basic fuel injection / carb heat FSX bug. Try to use the carb heat by using the associated key. With many add-ons this cures the icing problem where there isn't one IRL.

But for what sake is the carb heat knob down on the right panelside? I used it with no success, ia this dummy and not connected to the fsx carb heat key?

And why for a fuel injection engine.

Has this been solved?

You have carb icing. I know, there is no carb on a 210. This is an FSX bug that for some reason, thinks there is a carb there. Press the "H" key and it will clear the engine. There obviously is no carb heat knob on the aircraft since it doesn't have a carb (FSX just thinks it does). There is no definite solution to this other than to hit the "H" key when you start losing power.

Yep, what BeaverDriver said.