Idle issue '74 2.7 cis

[Overseas72]

1974 911 TARGA 2.7 CIS .
I've recently developed a idle issue. It has always taken a while to warm up to idle 20-30 min. Recently it has started to just cut off when i come to a stop . I can restart the engine and it will idle for a short time. The engine will serge up above normal idle then fall and cut off .
I have changed the gas - same problem

[Showdown]

You need to do a thorough test of your CIS with pressure gauges, until then you’re just guessing.

Look at:

Pelican thread “Cis for dummies”
Jim’s basement workshop

Once you have data, the problem can be identified and rectified.