80 911SC CIS Surging RPM on Cold Start

I've been through just about everything in the CIS - New w/u reg., injectors, sleeves, o-rings, intake runner gaskets/sleeves and still the car surges between 500-1500 RPM on cold starts for about 1 min. I figured it was a vacuum leak but now I'm not so sure. The injection pulls about 10" of Hg at idle. Is this enough vacuum? Am I chasing a ghost vacuum leak? Anyone with any suggestions or similar experiences? I know this is a semi-common malody in SC's, so there must be a cure out there.

had the same problem with my 79 911 trans and egnored it a while. But on my way to the repair shop to keep my appointment to repair the syncros the trans Locked up into 3rd gear. the gods were smiling on me that day and I was able to get it to the shop under its own power but it was close