I started to notice a slight "knock" or "Pop" coming from the engine. It typically only happens when I'm idling. When I crank the car, it seems to idle about 2k rpm, but dials down quickly, but it sits about 700-850 rpm. If maybe someone can put an ear to it Saturday at the lunch meet. Maybe MAF? Maybe O2 sen?

 

It could be as simple as a vacuum leak...remind me and I'll take a listen. After battling the hot summers for 11 years it wouldn't surprise me if a few vacuum lines have gotten hard and cracked.

 

True, the car is 11 years old...

 

Ditto
overnight mine stopped idling completely
Replacing all the vac lines is a decent place to start