Car Acceleration Hesitation

[Alexu]

I have a Mercedes C180 CGI (M271 EVO).
Recently received a code P233617, knocking in the first cylinder. I also hear a popping noise after I accelerate and release the throttle, and also hear some interesting noises coming from the intake side, such as burbles.
Has anyone experienced anything like this?

 

[crash_doctor]

This fault code should have relevant freeze frame data. Can you post them.
In general knocking could be a result of poor fuel quality, but than it would affect all cylinders the same way.
Single cylinder problems are often induced by the ignition system. If so, when swapping spark and coil between cylinder 1 and 2 the fault moves with to cylinder 2.
Some times intake leakages could cause such problems. If there are leakage, the engine should react for propane/butane (lighter gas) sprayed along the intake (near to the engine, where ducts already have been splitted).
Dirt or breaks/damages in the intake duct of the effected cylinder could also be a reason.
It is reported, that bad battery conditions could cause this, too. I have never seen this myself, but many times heard about.

 

[Alexu]

It might be the coil, the car has 190k km. and it still has the original coils. I also suspect a vacuum leak or some kind of evaporator leak. I often smell gas when I open the hood. I will try to swap coils first. Thank you very much!