I had the throttle linkage apart for cleaning and found a very worn roller (the smallest roller in the assembly, about 1/2" dia.) in the triangle bracket mounted on the intake manifold. The roller was flat-spotted and grooved. After two unsuccessful attempts with the dealer (they could only order the newer, I assume 280sl, part) I finally got the right one from Germany.
What a difference! The throttle action is much smoother and quieter (the new part is plastic, the old one metal). I am surprised at how much this one weak link was screwing up the action. If you have a minute to check yours, it is definately worth the effort. Five bucks and five minutes... I only wish all my other investments in the car were half as rewarding.
Best,
g
'64 230sl, fully sorted out...ooops, spoke too soon