About the tank
Your first line of defense against crud in the tank cloging your car should be the fuel filters, of which I think there are two.
Check to see of your filters are clogged.
There might be a tank strainer on MB gas engine cars as there is on Diesels. There should be a clear plastic filter on the gas line, and probably some sort of screen right up near the injectors.
I'd check this first. Messing with tanks is a pain.
On three occasions, I filled up my tank and discovered that I had purchased a tankful of water. This is a good reason not to buy gas or Diesel when it's raining or flooding, but it can happen anytime,
There is a drain on your tank. Check a shop manual , such as Haynes for the exact location if you don't spot it.
If there is water in the tank, it will sink to the bottom and will be easily distinguished from gasoline.
Drain the tank until all the water has exited and all that is coing out is gasoline.
Gas dryer (basically methol alcohol) will help to get rid of small amounts of water in the system.
I am not sure how one cleans crud from a tank, but I think it's as easy to do on the car as off, except for towing the car.
Cleaning a gastank is a rather specialized thing. Mostly small amounts of contaminants are removed with filters, and water is just drained off.
I would say that the most likely thing is that you have a tank full of water (a Diesel hose won't fit in your tank without your being aware of it.)
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