Lift???

AS none of you know i drive a 2001 Celica GTS..On my way to McDonalds earlier , i noticed that as i accelerated past 6k rpm that lift would not kick...I try full throttle in first and 2nd down a non busy road to see if something was the matter and still...It acts as if it hits lift but remains at its constant pickup...No power gain or nothing...And as i remember Lift made quite a difference ..Just wondering what was goin on, anything i need to check or any experience from others?...

Thanx in advance!

Ive read and searched and came up with it might being the Lift bolt?? Correct..How would that get changed or??