My 300SD has been hard starting lately. I'm reasonably sure my glow plugs are working, I checked them all not too long ago. The engine cranks and starts on a couple cylinders only with the accelerator to the floor. About 10 seconds after it starts it runs on all 5 cylinders with a big puff of fuel smoke. Once it's warm, or not too much time has passed, it starts and runs normally.

I am suspect of the injectors bleeding down.

Any thoughts or advice??

 

I would really check the glowplugs. When I replaced mine, it made a huge difference. Starts immediately even in subfreezing weather.