Rough idle
 

Hi All! I have a 79 911sc that idles rough and seems rough at a constant speed. It is strong when accelerating. The engine has been worked on by the previous owner. Any ideas?

It sounds like it is running lean. You may have an air leak or the fuel pressure may not be correct. Have you checked your fuel pressures? This is the second place to start with CIS after eliminating air leaks. Also I had rough running from old plug wires. Look in engine compartment in total darkness with engine running to see if they arc in the dark.

Targalid mentioned some of the top causes I've experienced on my 78. It might help to know more about what you mean by 'rough.' Is it missing? Does the tach move? is it 'hunting'...idling up, then down, then wandering? Does it surge then almost stall? I've had all of these :)