Long Warm Up and RPM Surge

[Mike80911]

Hello everyone new to this forum but not new to Porsches I have had 5 Porsches over the years 1981 911 1985 911 1985 928 and currently 2004 Cayenne and 1980 911 Convertible built from a Targa I can't believe this forum this is one of the best I have ever seen. Hopefully someone can help me with this I just purchased the 1980 911 it has 94,000 miles on it here is the issue. When it is cold and I start it the engine sputters and begins to stall this continues for at least 10 minutes or more. When I press the throttle to keep it running the RPM's shoot up to about 3000 and stay there for a few seconds even when I remove my foot from the trottle. Once it warms up it idles better but I still have the problem of the engine reving even when I take my foot off the pedal. When the car is idiling normally it idles at about 800 but as I said if I take my foot off the gas like when coming to a stop and press the clutch the idle is around 3000 for a few seconds. Any help would be greatly appreciated thanks Mike

[gsxrken]

Mike, sorry I can't help but you may want to post over in the 911 Technical forum versus the turbo section. Some real differences between the NA and the turbo cars evolved during the 80s with respect to the type of fuel injection used.

[Mike80911]

Thank you as I said new to the forum and did not realize I was posting in the wrong area I reposted it in 911 Tech Forum thanks for letting me know