Hello fellow w208 owners, for the last couple of months I have been having an issue I can't seem to figure out and was hoping I could get some answers here. I have a 2002 CLK 320 with about 150k miles on it. I bought the car about 3 years ago with about 120k on it and use it as my daily. Since the first day I bought the car I had issues putting gas into the tank because the pump would shut off every couple seconds even though the tank was not full. I would have to pump gas slowly and at different angles sometimes. I used to pump gas at Arco gas stations since it was the cheapest but figured that if I started using chevron it would help out with my problem due to their techron additive(Yes I've only put 91 octane). At first it helped out and I started to have that issue less frequent so I added fuel system cleaners here and there to help out a bit more, since then I rarely come upon that issue. Now the reason i'm making this post is because i'm having a problem with a small rough idle that comes and goes only when I come to a stop after going full throttle. It only shakes a bit when I come to a stop, goes away once I drive off, and does not return again the next stop unless I give it full throttle again. I figured it might be my spark plugs since it was near the time frame for new plugs. I changed my spark plugs about 2 months ago and still have same issue but now it has became a bit worse since now I have a new problem which makes me believe is connected to the same rough idle issue. Now every time I try to launch my car from a complete stop it jerks a couple times till i get into high rpms in first gear and after that it drives normal. If I go full throttle above 4k rpms into 2nd gear it works normal as well without hesitation.The car jerks about 3 to 4 times pretty hard before it drives smoothly. It jerks so hard that it caused my brake booster hose to break off causing a pretty scary drive since I thought I had no brakes to stop with. My conclusion so far is that it has to due with the fuel system but i'm not exactly sure with what? Clogged fuel filter? faulty fuel pump? clogged fuel lines? dirty fuel injectors? or maybe i'm wrong and it's something completely different. I'm leaning more towards a clogged fuel filter since the car is somewhat "old" and I don't believe it has been changed. Do you guys have any advise or ideas of what it could be? Any advise is appreciated. Happy holidays (:
No CEL lights are on.

 

Here is what I think your problems are being caused by:

When you add gasoline to your tank, the tank isn’t venting (e.g. air is being displaced via vent lines. The W208 has a saddle-back gas tank with two vent lines. Those two lines go to a charcoal canister, and from the canister out to another line which feeds a valve, and so on. A common culprit is a clogged canister. Why is the canister clogged? If gasoline gets into the canister, by overfilling the gas tank, the charcoal will break down and clog the system and very little, if any, air will be able to pass through. If air can’t leave the gas tank, gas won’t go in. The canister will also clog due to old age because gas fumes will break down charcoal as well. The fix has been to either to replace the canister ($$$$) or bypass the system, with some new lengths of hose, tees and hose clamps ($). While faulty venting is a PITA in filling the tank, it typically does not affect engine performance.

Your more recent engine performance issues may only be due to lack of fuel filter preventive maintenance. As shown in the below fuel system diagram, in addition to being clogged, the fuel supply system pressure is controlled by a pressure regulator, which is integrated into the filter.