Idle problems
 

I have a 1978 911sc. Most of the time it idles at 2000 RPM. Then sometimes it idles at 1000, then 1500. Rarely it barely idles and almost stalls. I have had it in the shop and they tell me that it is set where it is supposed to be. Any ideas?

Steve,
Next time it's idling high, wedge your foot under the gas pedal and lift up. If the idle goes down, then your throttle linkage needs to be lubricated.

If that's not it, next time it's idling high, hold the brake on and let the clutch out in first a little to force the idle down. If the idle stays there after you put the clutch back in, it's probably the deceleration valve.

Doug
75 911S