I am by no means an expert, but I have been really getting into my Benz this year. I found this forum and I have been working on finding nuisance problems and fixing them. I've managed a couple of things, and I feel a little more informed about the car now that I did before - a great feeling!

To answer your question, here are my thoughts:

a) fuel pump - possible that it could be failing.
b) clog in fuel line, doesn't seem likely.
c) fuel filter, same as b) doesn't seem likely either.
d) fuel injectors, impossible. Car will run with dirty or clogged injectors, and really they can't clog all the way and all 4 at the same time.

e) Not sure about what this guy does, I got one for mine from a junk yard, replaced it and see no difference (I have a "hard to start" problem especially when hot and sitting for a while). Its a cylinder with a vacuum hose hooked to it. I doubt that you will suddenly lose power like that with it.
f) fuel distributer, no knowledge about this guy.
g) fuel pump relay. I found mine recently. Its under a black cover the size of a cigarette box. Its a relay. If you pull it off, fuel pump will not run. Without fuel pump, car will run for 1 second and die. Not likely this is it as if your fuel pump was losing power, your car will die almost instantly. There is no such thing as using up fuel in the lines, the system needs pressure from the pump to operate the injectors, and with no pressure, no fuel will flow. Eliminate this one as the cause. You can unplug yours and see what happens when you try to start the car without it to confirm.

How often does this happen? Can you test it in your garage? What I'm thinking is that if and when it happens, if you remove the air cleaner and spray some quick start in the air intake, will the engine run? If it will, then its a fuel issue for sure. Can you explain number 1. again in your problem discription? I am trying to think about the solution for you but maybe more info would help. Is your car automatic or manual?

Oh yeah the vacuum guage will move even if you turn the ignition off while driving (I have a manual transmission so the engine still turns with the wheels). Its just a vacuum sensor and as you throttle up, you lose suction as throttle body is taking in air. So its only a mechanical guage and means nothing (its going to move always with the engine turning running or not).

What does number 3 mean? Crank crank crank for a minute to go or wait 1 minute, click crank for a second and its running like normal?

Let us know and maybe more info will help us here give you a better answer!

Good luck!

-=>Raja.

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1983 MB 190E, bought from Germany and shipped to the US in 1986.