Troubleshooting 1982 Mercedes 300D

I can't give you specifics without looking at a book (don't own that one)

You need to look at the ignition switch / circuit. the key switch signals the glow plug system, AND should kill the run circuit at shut-off.

after reading an earlier post, I found and replaced the glowplug fuse which solved the starting problem.

cool. that would have been the bigger of the two troubles, no doubt...

(still guessing the no shut off is mechanical in nature)

i have an 83 300D and i had the same problem with the shut off. the problem in my car was that the vacuum hose was disconnected with whatever makes the car shut off. in order to fix this i had to disconnect the vacuum hose that makes the door locks lock/unlock (witch i was fine with because the mechanic wanted to charge to have both fixed and i didnt think it was that big of a deal) but if you pick up one of those handy haynes repair manuals you could look in the trouble shooting section and it should say something about the engine not shutting down (Not 100% but if its not in there its in the book somewhere) GOOD LUCK

and another thing.. DO NOT shift the gears from reverse to drive while the car is still rolling back hahah.. i have been doing that for a while and something broke in the car (Not sure what it is) but now the car doesn't have any forward motion until it shifts itself into 2 or even 3 gear. let me know if you know what the problem is.

GOOD LUCK