Wandering idle when cold

[Z06C5R]

I finally got a good chance to start checking my new 944 out this evening... Of course it has lots of little bothers as one might expect from a 23 year old car, but the one that has me concerned is it's behavior when cold:

The car has been sitting in my driveway since Monday night, enduring temperatures anywhere from freezing to almost 60. I started her up and let her idle for a bit, and noticed the idle was wandering quite a bit - maybe between 500 and 1000 rpm. After a minute or two it will stabilize, but occasionally have a random drop in RPM which actually stalled the engine a few times. Low fuel pressure maybe? However, once it's been driven a bit and brought up to operating temp, it idles perfectly at 1000 RPM.

Any ideas?

[nynor]

you have a vacuum leak.

[OnTheRun2]

I agree with nynor.
An easy way to find where it is, is to spry each line and fitting with WD-40. When you spray the leak the idle will stabilize for a noticeable amount of time.

[Z06C5R]

To update: I had it out today for all my registration crap, and I noticed it wandering a bit when warm; between 1100 and 1000 rpm which seems high to me.

Also, I did a quick vacuum-test I picked up working on my Z - You pull the dipstick out when the engine is running and if the idle drops, vacuum is good (the idea being that by pulling the dipstick you're introducing a vacuum leak). On performing said test, my idle dropped... I'm sure it's not quite that black-and-white, but I'm just throwing that out there. I shudder to think how many potential points for leakage there are on one of these new-fangled FI engines.

[nynor]

not the same on this engine.