Date registered: Jun 2010
Vehicle: 1966 MB 200; Porsche 914 (6); Porsche 914 (Chev 350); 36 ford
Location: Sunnyvale, CA
Mentioned: 0 Post(s)
Quoted: 19 Post(s)
If you keep it running until it reaches operating temperature, does the idle smooth out? Could be a cold start issue.
What do the plugs look like? Sooty? Are they all the same?
Do you have a vacuum gauge? You should have around 18 at idle. (I am not that familiar with that car, so, it can be somewhat different.) It should be steady.
Did you check all the vacuum lines? Don't forget the line going to the brake booster. The booster itself can leak, creating an erratic idle.
On a car that old, it could be problems with high resistance grounds. Check all the grounds for good contact.
Someone more familiar with the EFI on that car can help more, as some of the sensors could be bad, such as the MAP, temp sensors, etc.