MartinB6

hey guys, so i have a 2004 a4 quatro. 124km and im pretty new to audis
about 2 months ago i got the apr software with the bigger injectors.

THE PROBLEM
seems to be only in 5th or 6th at about 2900rpm, when i accelerate the rpms rev to about 3500-3800 then drops down to catch

it first happpend 2 weeks after the software the guy said run the throttle body calibration. so i did and seemed to work. (also should i do the throttle body calibration on hot or cold engine?)

but now it seems to "slip" the same way and the calibration didnt work.

so can it be the clutch? even though i dont touch the clutch it will still slip upon acceleration?

OR

MAYBE could it be the trottle body itself? do i need a beefier TB?

any inputs help.

also if anyone has and suggestion what to do next to build the car more solidly id like to hear them.

i have DV ready to go on and probably do exhaust next