I've got a 1985 300d that had been sitting for 8 years and have been trying to tie up the loose ends. I have installed rebuilt injectors, adjusted valves, changed filters, chasing a rough cold idle. It is a random miss and in between the rough hits it runs very smooth. Once it warms to about 60c it is acceptable with the random shutter gone. The more I have run it the closer the shake gets to fully warmed up(it's getting worse and missing longer). There are no fuel leaks that I have found. The one thing I have discovered is bubbles in the brown clear fuel line that comes from the banjo fitting on top of the filter to the inside of the IP. Is that normal? I used a small flashlight to look into the line and could see small bubbles at slower speeds and the line clouds with higher revs. It will clear out with no bubbles idleing for a few minutes. Rev it up and the bubbles return. The main complaint is the cold idle shakes. The engine has about 160k on it and the glow plugs lite(checked with injectors out). I have not been able to do a compression check. Oh! there are no bubbles from the lift pump to the Filter. Thanks for any ideas!

The bubble are probably the source of your missing. I would first try tightening all the hose clamps in the engine bay and at the tank in the rear, and also make sure all your banjo fittings are tight. Make sure your spin on fuel filter is tight, and that the surface that it mates to is not scratched up, and that nothing is leaking out of the top of the filter stand. If it's leaking out of the top, where the bolt is then you need either a new crush washer or you need to replace the o-rings on the end of that bolt. If none of that helps, I'd start looking into replacing all the fuel lines. Sometimes the fuel lines get cracked and let air in but don't always drip fuel out.

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BD300TD thanks for the help. Now that bubbles are bad I will re-visit my new fuel filter. I replaced the Bosch filter with a filter that seemed too big for the MB filter stand. It seemed to put pressure on the banjo fitting and I did not move it because the fuel line was short. This did not seem right so I will start with that assembly and another filter. Another question that I did not ask was what are the symptoms of a tired motor? I would call the blow by it has as moderate. It will not blow the cap off at idle but if you have a nice shirt on you better stand back. Would this missing be caused by that? The car fires instantly every time and does not smoke. Also do diesels suffer the same problems as gas motors from sitting? Think it may need to run a bit after getting the bubbles out of the fuel to really run right and tight?

another possible source of bubbles that I had on my 300CD was the hand pump to bleed the system. Sometimes they start to suck in air, but also check what Biodiesel said too since its been sitting for so long, good luck!