Given your description below, I'd say it's NOT the injectors. Immediately before I had the injectors rebuilt on my '83 240D, 250k miles, my symptoms were:
* LOTS of clattering/pinging noise when engine is cold. Noise got significantly louder if engine was revved. Noise goes away as engine warms up to normal temperature.
* Relatively poor fuel economy. 24-26 mpg when I should be getting 28-32.
* Somewhat excessive smoke (even for a diesel).
I paid a local shop $115 to clean and rebuild all four injectors, including brand new nozzles on two of them, which cleared up all the above symptoms.
In regard to your problem, it certainly wouldn't HURT to rebuild your injectors, especially if you have never done so in your 186k miles, but the injectors are probably not the cause of all the symptoms you listed.
'83 240D, 250k miles