How do I know if I need new O2 sensors?
 

Well I haven't had a CEL in ohhh forever. Did my regular maintence and cleaned out MAF with the CRC spray. How do I know if I need new O2 sensors?
One thing does bother me. When I'm in first gear and I let the car coast (foot off throttle) I get a fluttering sound, (like blowing on a sheet paper paper) coming from the engine. What's that all about?

I think the O2 sensors are supposed to be replaced at 60k. You'd need to check on that. I got the dreaded CE a year into ownership and it was oxygen sensor-related, so I replaced all four. I quickly discovered how much better the car performed, idled and gave 3+ MPG better fuel economy afterward.

Someone will have to tell you about the hunting idle issue you have. It would appear there are numerous sources and combinations that can cause this.

i'M nowhere near 60K miles yet. Probably another two years at least. I'd rather change things before they break if I can get a good deal on parts and labor.
What's a bad air-oil seperator sound like?

I don't know what it sounds like because I've never had that happen to my car (knock on wood). However, I thought of it when you posted this issue.

You can check it by taking off your intake to see if you find oil in there. How involved that is I do not know.

air/oil separator symptoms
 

As the A/O S. fails, there will be an oil buildup in the intake, particularly near the throttlebody. When the AOS completely goes, it will cause the car to smoke/burn oil...you and everyone behind you will know about it then!

hey guys, I had a cel light recently w/1130 code and was pointed in the direction to look at the air intake. Does anyone have a pic of what the air oil seperator looks like?

try a search on Rennlist. I believe someone posted the Porsche Electronic Catalogue diagram in a thread on this topic.

Here it is from the Porsche website:

http://www.karrera.net/en.partscatalogs.html