My '82 300 sd was running, but loosing power( didn't want to go over 62mph) and was idling real rough and smoking when at operating temp.
It sat a few days and I adjusted the valves( they were all but three, way too tight ) put everything back together and went to start and it fired up and ran for about 8 seconds, then quit( like it ran out of fuel )
It did this about 20 times.Then on a whim,I removed the fuel cap ( I've been suspecting the tank vent is not working properly ) it had a hard suction on it.
Then it started and slowly gimped itself to an idle.
I stopped it and cracked the filter loose and primed it( the primer pump is leaking pretty good while pumping now)
Then it fired up and idled fine. got it up to operating temp and idle nice and smooth now and no heavy smoke, backed it out of the driveway and tried to go uphill and it was like it wasn't getting any fuel. Had to let it roll back and put it back in the driveway.

Both fuel filters are new a few days ago ( no miles on them)

Does anybody have any clues on this one?

Thanks--------Robert