Oil deposits in the thorttle body

I changed the air filter and notice that some rest of oil or something brown like oil is there what can be the cause, i had also notice a hissing noise but i can find it i alredy change the lower intake gastkets and also replace an intake main fold runner control that was screwed but i still feel it lousy or i dont know how to explain it enlgish is not my native language, thanks in advance for your atention

Latinoguy,
Your profile says that you have a 1998 windstar, which is very similar to my '96.
On my '96, the PCV valve is in the rear valve cover (I think that they started putting the PCV valve in the front valve cover in 1999).
The line from the PCV valve runs to the top of the upper intake manifold.....through a rubber elbow.....now that elbow can develop a crack on the inside part of the elbow......which causes a vaccum leak.
This is at the throttle body end of the upper intake manifold.
It is NORMAL for some oil to enter the intake through the PCV line.
What I have found is, that some of the oil comes out the throttle body into the flexible hose that runs from the air filter/MAF unit to the throttle body.
Some after market PCV valves can permit too much flow, which pulls more oil into the intake.
But I even got some with a Motorcraft PCV valve.
You do not want to reduce the flow through the PCV valve, as it is removing bad stuff from the engine.
Some oils have a higher evaporation rate than others.
I put a "catch can" on mine.....pictures of that are in my pictures that the link at the bottom of this post will take you to.
I also put Redline 5W-20 oil in at about the same time.....which has a VERY low evaporation rate.

My honest opinion?, if it is not real bad.....don't worry about it.
If it is getting over to the MAF....you might want to try what I did.
I bought the catch can kit online.
But.....I had no problems caused by oil in the intake for 168,000 miles.
I did it thinking that it might reduce the need to clean the EGR ports....as they become clogged by the EGR gasses meeting the oil vapors in the intake.
But then.....I did not have to clean the EGR ports until about 140,000 miles.

Thanks for your answers guy like you make the life easy, actually i alredy bookmarked your web page and already cleaned the egr ports i will chek that elbow thanks for being like you are i have alredy read a lot of your post God Bless you and your family.