high sprite consumption on 3.6

Hello have long been the problem with my 3.6 v8 that it "far" too much fuel with too little power consumption.
So I figured out for myself that he spent 100 km around the 22l super - in places and on country roads of course ^^
However, quite irregular when I give Gaß it does not accept it at all in the first few seconds and at the next moment the engine accelerates normally.
This happens in the warm-up phase. Is it possible that this has to do with the knock sensors? or wodran do I even notice that these are defective?

Greetings Philip