Lifetime Premium Member
Date registered: Sep 2008
Vehicle: 1975 450SL
Mentioned: 2 Post(s)
Quoted: 15 Post(s)
Would your '75 280c have a D-Jet injection fuel system? If so, there is a good chance that a vacuum leak would be the culprit. These things seem to run on vacuum as much as gasoline.
I'd recommend that you start out with the tune-up basics: Check the distributor cap, plugs, rotor, dwell angle (yes, these things DO have points), timing, and idle speed.
Eliminate the "cheap" stuff before you start going for the expensive pieces.
Remember: It's not just a car. It's an Adventure.