wOOOOw

Hi all,
I've a 2000 1.8i (non turbo ) A4 the car start and runs good asides from the weird problem I cannot find anywhere a solution for. Don't wanna parts cannon it lol 😆
So, if I'm taking off 1st gear seems sluggish until 3k revs
I thought hmmm 🤔 so I tested in 2nd and 3rd respectively at different speeds. Same result it's like the car drags it's *** to 3k then bam normal acceleration (it feels like VTEC kicking in if that makes sense)
I know the NA version of this model is not a fast car but it's not at all right...
Has anyone ever encountered this or knows what the issue.

Car is
Year: 2000
Miles 129k
Recently had all new filters fuel oils etc
Coil pack and plugs were done also.
MAP sensor was replaced too by previous owner just before I bought it
I was told 02 sensor by seller but I'm not sure ,I got it cheap so I'm not worried but its wrecking my brain I'm pretty clued in to cars but this has me stumped 🤔