‘07 Cayman S (987): Surging Idle/RPMs

[CJFusco]

I have an interesting issue in my 2007 Cayman S with 67k miles. The car has a surging idle when warm, which extends to on-throttle behavior: when one’s foot holds the throttle steady at what should be 3K RPM, the engine surges rhythmically between 2K and 3K.

I saw recently that one of the coil packs was starting to crack, so I replaced coil packs and plugs preventatively, with fingers crossed that it would cure the surging RPM issue, but no dice.

I’m suspecting either a vacuum leak somewhere, throttle sensor, or possibly MAF sensor? Any thoughts?

[CJFusco]

UPDATE!
I plugged in my tuning software, and found one code: 1095, which is “mass air flow ahead of throttle vale implausible (too high)”. Now, the car does have an IPD plenum and 997 GT3 throttle body, but it’s running a tune to adjust airflow and has been doing so for several years with no issue.

On visual inspection, I did find that one of the hoses running from the the AOS to the TB was maybe a little loose, and also had some oily residue around it. Pulling that hose, it looks like there is a little bit of oil in the hose. I disconnected the hose from the AOS itself, and there was more oil at that end. See attached pics.*

So: follow-up questions: 1) might this loose hose (if it was indeed loose) have caused that idle surge and error code? And 2) is the oily residue a warning sign that my AOS is beginning to fail?