It was not at all like this. It was very fine before (at 90 km/h in 5th and 2900-3k rpm). And another thing: at idle with engine at normal temp (85 C) when a fully press the accelerator, rpm only goes up to around 4,8k-5k. And that is way to far from 6k or 5,8k. I tried to adjust the idle rpm from a screw at the end of a pipe, from the manifold. Adjusting from this screw, the extra air enters after the AFM .
I also learned that there is another screw to adjust the idle rpm, near the throtlle plate.
The thing is that the car has a very good acceleration but too early in the rpm. I mean it goes like a rocket from 1.5k up until 2.5k-3k, then the acceleration is slower. Max torq at 4.5k and max power at 5.8k. So I only use the engine for half its power and torq. How come ??/ Whats the problem? Could be the lambda sensor?