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!