hey guys im in need of more help so can someone please assist )

i ran my 18ss+ today and after a few tanks on full throttle the engine was reving but there was no increase in speed or acceleraion

the diffs are perfect and shimmed perfectly so i know its not that

i beleived its gonne be the slipper. its tightened all the way down and then backed off for about 3mm.
if i let the car cool down it will be back to normal

anyone else experience this and how was it fixed

is it actually the slipper thats at fault or could it be something else

everything else is tight as they should be