ok the problem seems to have come back. I've posted the video here.
Startup Issues with my 986 - YouTube
You can hear the problem (it's like a high pitched vacuum cleaner) from about 0:05 all the way to 0:48 where it just suddenly goes away. If I rev the engine it comes back (this is new behavior). This is coming from the right hand side intake.
I only hear the noise on startup and if the car has been sitting for a while.
Trips to the shops i.e. frequently starting do not cause the problem
It's usually first thing before work and then when I'm leaving work..
Any help appreciated.
bobby