I need a technical help

Camshaft position sensor ?

 

Simple really. The OP mentioned spark plug work resulting in not just a misfire but seriously rough running condition. I never said there is a distributor in this vehicle. I merely said the symptoms reminded me of an ignition firing order problem.

I am not a mechanic. But I am an engineer. Since the OP had work done, or did work, on the spark plugs just before the symptoms appeared, a quite logical conclusion is that they are related. Is it guaranteed that that is the problem? No. Does further diagnostic work need to be done? Yes.

Let's take a look at the "everything the op recently did has to be looked at" for a moment:

1. engine oil change and oil filter change - this could cause a misfire in some situations. But, it never has in my experience. So, I disregarded it.
2. gear box oil change - ditto
3. fuel injectors ckeaning - since this usually takes the form of merely adding a fuel additive, I disregarded this too.
4. spark plugs change - Hey! Look what's left?!?!?!

That's how I got to a loose cable or other problem with the spark plugs being the likely candidate for the cause. If it turns out I'm wrong, I'll say to myself "well I'll be damned" and move on.

 

My guess is one of the connectors (at the spark plug end, lol) is not seated properly, one sparkplug is failing to fire? Or would that result in much more extreme symptoms?

 

Have I missed something, but to me it's not clear if the OP had the problem before and did the work to try and cure the problem or he did the work as routine maintenance and caused the problem ?

 

We have assumed the latter but, because English is not likely the OPs native language, it may be the former.

 

Reading through it again I think I missed the word "then" after the servicing bit.
In that case, I'll go for (in order of probability):
1. damaged or loose spark plug coil connector.
2. significantly overfilled oil
3. damaged or dislodged other electrical connector somewhere.
4. injector cleaner damage to the CAT.

Another possibility, I think I read somewhere recently in another thread that the ICE runs rough with the oil cap off, so if it's off or loose could that be it ?