I took these out this morning (before kids woke up - can you believe it?). The one on the passenger side required a creative rench angle, and took like 10 min to loosen a bolt. The one on the driver's side was totally dropped. The way it looks, when it is dropped, it'd block the oil path by 1/2 ~ 2/3! Depending on which direction the oil runs, it was kind of scary. I can't say the effect for sure, but the idling is very smooth now. I have had multiple occasions of mysterious sudden stalling in the summer. I can hope (can't I?) this resolves this issue Subaru tech couldn't figure out.