a very sporadic problem

Moin Moin………. So young, I really have a problem. I have the b4 ABK 115Ps 2.0L. And last week I had the problem that fell to 0 during the drive from one to the other sec of the tachometer from approx. 2500-3000 unmsrotungen, the car also did not accept gas. I rolled out then and then turned it on again……short time later it happened again, I drove again and after the 3rd time the car went on again after 5min. A few days earlier I had to overtake it, which he took alternately gas but did not after that again, so the car totally jerked and I was able to overtake with trouble and need. After I lit candles (they were totally through) and solderers changed hoping to have solved the problem, especially since it was bad when it was wet and moist, but he didn’t do this anymore after the change. yesterday was the same try again, I drove from the parking lot and was in 2nd place. or 3rd walk (before I was always in the 5th) and again he went out. But this time I came home with only one stop. today was nothing… the distance on which this always happened is always so 7km. Can anyone help?