Valve on top of engine?
 

Ok I have been living overseas a few years now and have really gotten out f the groove of fixing cars. So I bought a used 2008 Mazda3 hatchback. I noticed it was idline slightly rough,, and the rpm's are at about 500. Well, I popped the hood thinking I would turn the idle control screw on the throttle body,, but as it turns out, cars nowadays dont use these. its all electrically controlled.
Here is the issue I see now:
1. Rough idle,, 500rpm, when I apply slight gas and bump it to 750rpm, it idles smooth. How can i increase the idle rpms to 750 permanantly?
2. When I popped the hood, there wa sa white powder on my valve covers. I removed the mazda3 engine cover,, the POS that just clips on, and noticed there is a white cotton sort of pad on the underside........
Well, on the valve cover, next to the oil cap.. passenger side, there is a solenoid where all this white crap seems to be coming from. it looks like it is rubbing on the engine cover. However, when I was looking in there, that solenoid made a hiss sound. Also now when I drive, i tend to hear a hiss coming from that side of the engine from time to time.

Iam not sure if I am just paranoid or what, but I am about to drive on an 8 hour road trip and dont want to die in the desert.
Anyone have ANY sort of helpful info here?

I need to know what that solenoid is, if it tends to go bad, and how to adjust that idle rpm.
Thanks a lot everyone. It's my first post here, I wish it could have been something positive

anyone?

There are two valves there, one is a tumbler solenoid, and I forget what the other is. But if it's making noise it's probably the source of the idle issue.
I don't think there's a control for the idle, it's all computer controlled and not adjustable as far as I know.