It might not be the main cat underneath the vehicle, but rather one of the two precats further upstream. This is the reason I recommend people get an OBD2 scanner or some kind of software hookup if they have a laptop so they can see what is occurring. If you have a blocked cat, the acceleration is going to be noticeably diminished.

One thing I could recommend is you disconnect your battery cables for a few minutes, reconnect them and then drive a about 15 minutes, half city, and at least one period of time where you can get above 100 km/h even if for a few seconds. And see if the situation is better, worse or the same as before. It is possible a check engine light may come on (and that would help toward diagnosing the issue).

I won't disregard the idea that bad gas can cause issues with cats. I had such an issue in Mexico one time driving in a rural area where the gasoline was adulterated.