Pertinent Info:
2001 Boxster S
60,000 miles
Original AOS from what I know, had the car 37,000 miles and I haven't replaced it.
I was driving today, came through a roundabout in a spirited fashion then I had to stop a few hundred yards down the road for a car to turn. The Boxster started to stumble and act quite strange like there was a misfire. I drove another hundred or so yards and it threw a flashing CEL for no more than 10 seconds then it went away completely. Seemed fine when revved but idle is rough and unstable around 700 rpms.
Got the car the less than a mile back home and parked it. Slight smell of fuel or oil, wasn't sure what.
I let the car cool some and restarted. It fired back up no problem, no smoke. Gave it revs in neutral in the garage and all seemed fine. I opened the oil filler cap and it was easy to take off but I heard a vacuum type sound from under the car right when I took it off and the car started to run worse. Then I let it sit back at idle and it started to stumble again and eventually the CEL came back on but not flashing.
I've had a similar experience a few months ago that the car stumbled, but no CEL and it went away that day and hadn't come back. I ran Techron in the fuel for two tanks and it seemed fine. One random day in between I noticed a small but not unusual plume of smoke on startup, but nothing ever while driving.
So here's what I did today, after a search through the posts here I went and pulled the engine cover and looked around. I notice one pipe has a fair bit of oil on it near the AOS, but not sure that's the problem. I pulled the vent tube that connects the AOS to the passenger side intake and there's a good bit of oil in there. It didn't run out but it was more than expected.
Any thought on what's going on? Since it's Sunday I haven't had a change to get any codes read, but I may try to get to the dealer or at least get the codes pulled tomorrow and see what's what.
I'm thinking the AOS is toast and needs to be replaced, but would love opinions and help.