I finally got both the injectors changed in the 260E 124, and 300SE 126.
On the 124:
I noticed a prompt response on the kickdown, and the lightness in touch on the gas pedal. Previously, it was sluggish. Now it behaves more civilised with an even-power distribution at torque. Relatively ease in projecting 0-100 km/h without the sudden surge and slug.
The engine sounded smoother too - not so much like a diesel powered powerhouse.
I felt it was worth the while replacing the injectors - despite the advise of some.
On the 126:
The noticeable difference is in the accelerator. It seems much lighter than it was before, and the delivery of power could be felt - smoother than it was and with a gradual silky acceleration. Response was more sensitive on the depressen of the gas pedal.
I also changed the brake-pads (had original, and refitted original). Applied the brake paste AND cleaned with a generous spray of Brake Cleaner over the disc and within the brake-clips. Noticed silent-braking now. Am wondering how long would it remain silent before the squeaks return.
Summary:
It WAS necessary to change the injectors.
Thank you all for your comments and advise, to which I am grateful and guided.
