Engine speed breaks with light gas enter briefly

Hello guys, I have a question? it’s about my Benziener Audi 1.8 , B4 avant Bj.1994 (in case of engine stationary gas in order): when I then give a light gas, the speed breaks briefly (but then rises again quite normally high). I noticed that when the gas tilt lever on the injection system, rotate after a few mm, one hears a quiet click; and that’s the moment when the speed breaks briefly (but then to turn normally high again). If I stay exactly at the place d If I keep going, the engine turns normally high, but also when I’m driving, that I have the drop-out after giving gas, and the engine sometimes runs out completely. What could be the cause of this?