180E stalling out

The car has been stalling out more and more. It began when I started the car it would nearly die then come back up to idle. Now when the car comes back down to an idle, after driving around the car for a while,
it will start to stall, and if you step on the gas hard it will, sometimes you can save it if you feather the gas pedal but not always. The other day it stalled out in traffic, tried to get it started for 20 minutes, called the tow truck, he came over and started it fine drove it onto his truck, then towed it home and it started fine when he took it off the truck. It has stalled out a couple times before that too, taking awhile to get it started, a lot of cranking, but always started. Is the problem with the injectors or is it a clogged fuel filter? Not sure where to look for the problem at, any suggestions?
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I would start out looking at the fuel pump relay... Take it out and look at the date stamped... if it is really old... you really need to change it. On 190E... it is located behind the cover behind the battery. Depending on year and make... it will say Kickdown on it.
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Given your description, I suspect either a fuel or vacuum problem, not an ignition problem.
If this began suddenly I'd first suspect bad fuel or a vacuum leak, if it's continued for at least two fill ups I'd suspect the fuel pressure or its regulation.
A vacuum leak allows unmetered air into the motor; that air dilutes the air / fuel ratio so the motor has trouble idling. At idle listen for a hissing sound from the area of the intake manifold and look for a disconnected or broken vacuum hose that is or should be attached to the intake manifold. You don't notice a vacuum leak while driving because it's a small leak that gets smaller as a % of the total air as motor speed and load increases - but at idle it affects the motor.
The fuel pump is electric and ought to put out a copious stream AND achieve a pressure of about 45 psi. An old fuel pump may not be able to do those things, but wait, there also a fuel pressure regulator and if it fails the engine's control system gets confused.
You don't mention any difficulty accelerating or climbing long hills - both of which take a lot of fuel so that implies an adequate fuel supply and therefore a clean fuel filter.
If the fuel is not a suspect I suggest you focus on the fuel pressure regulator which is attached to the fuel rail that feeds the fuel injectors. This device looks like a small can and it has a thin rubber hose attached to it that's connected to the engine's intake manifold. With the engine recently shut down pull the rubber hose off the regulator. The regulator needs to be replaced if fuel dribbles out of its port. These are not cheap so shop on-line for a replacement.
If the regulator is OK then a shop ought to test the pump's output pressure.
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If I might add one more thing - do you have an immobiliser fitted?
My 190e had very similar symptoms which turned out to be a fried connector (the only non standard Merc part) linking the fuel pumpup power supply to the immobiliser box.
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Change the fuel filters(s). 99% chance that's it.
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Richard Sexton | Mercedes stuff: http://mbz.org
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