I'm in the midst of taking my 300E out of moth balls. I ran it briefly a few times in the last few days to move it around, check the a/c and such. It refused to idle except for some times when you eased the speed down to an idle. This led me to think that I might have a sticky flow meter.

I found a broken vac line from the air filter breather hose that goes to a diaphragm of some sort. I fixed that and while I had the air filter off I checked the flow meter for smoothness and it all felt good.

I then drove it to town to wash it and wash down the engine compartment real good since I will probably be replacing the a/c compressor soon. Once I got a few miles down the road and stopped at a stop sign it was idling fine. Several times rolling down the highway I kicked it in neutral (manual transmission car) to see if it would idle and it idled just fine. I got to the car wash and it idled just fine. This led me to believe that the problem was only a cold idle problem.

It ran fine and once I got back close to the house I let it coast in neutral for the last quarter mile or so and it idled fine at first, but then died about the time I turned in the driveway.

I plan on checking fuel pressure next. As history, I replaced the coolant sensors not long before it went in moth balls. As I recall this problem was begiinning about the time I put it in moth balls.

Any ideas are appreciated.

How about these for ideas:

1) idle air control valve and its 2 vacuum hoses;
2) deceleration micro switch
3) throttle valve switch
4) airflow sensor position indicator
5) crank position sensor

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't