I think if the engine mounts are saggy, the linkage adjustment to the accelerator will be out.
I had the vertical connecting linkage that goes down from the upper linkages to the lower lever to the accelerator pedal, actually using the inlet manifold as a stop.
This made it impossible to adjust the air fuel mixture.
After eliminating all the play in the cross rod and the ball and socket connections, replacing the engine mounts and setting the linkages correctly the vertical rod is now about 0.5 mm away from the inlet manifold and the car is now correctly adjusted.
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto