Need some help bad

[Badass_yellowGT]

hey all
i need some help this is my problem. about 3 weeks ago i had the head swap thing done on my 98 gt and everything seems to be running fine car idles great and has awsome power i run 94 octane fuel and since the swap when i hit 4,000 rpm the engine kind of hesitates a bit it feels like the clutch is slipping and catching but at 60 MPH in 1,2,3rd gear it only does it when i put the foot to the floor if i gradually rev through the band i don`t get it, i have no pinging noises which makes me kinda hesitate on the detination idea since it is only during full throtle runs and not graduall increase in the same gears ,so does this sound like my clutch is letting loose because it can`t handle all the extra power with my mods or is it detination your thoughts would be much appreciated and would this throw a code if it is detination i don`t want to ***** up my engine i have never experianced detination and could use some help i`m running stock timing