I'm a neebie here & new to MB diesel (6 months). Coming from BMW e28 535i backround, I'm relearning how to drive PATIENTLY. I have an '81 240d, stick, manual everthing w/ 236k miles that has alot of the above symptoms. I've put approx 15k highway miles on her since purchase in 2/11. 214 miles a day on highway, I've lost 2 mpg, down from 28 to 26 hgwy avg, and it seems alot noisier (nailing?) I was not pleased w/ 28 mpg hgwy (no air & 70 mph cruise) now I'm down to 26.

Car was MB serviced until 2 yrs ago & I've got the records. Nothing shows injectors or timing chain replacement. I bought it w/ intention to convert to Veg oil, but have not.

Concerns:
1. Should I replace the injectors as a regular service item?
2. Replace or adjust timing chain?
3. Have injection timing checked/changed?

Items done:
1. 4 new CV joints in rear.
2. Redline gear oil in rear.
3. Redline MTL in gearbox
4. All new glows
5. Valve adjustment & cover gasket
6. New return lines from injectors

Any help will be appreciated, as I'll likely have to find/pay a mechanic here in FL to do the work. I Don't feel I have appropriate tools & diesel knowledge, though I'm pretty proficient with a wrench.