Aiight, I bought the car with ~45K miles and now it's at 53K, I don't know if the clutch has been changed in the past but now, when I'm taking off from a stop, it feels like something is slipping. It only happens when I give it a lot of gas (almost flooring it), and usually in the higher RPMs, like 4-5K. Then again sometimes I will totally floor it, spin the tires a bit, rev all the way to 6-6500RPM then shift and go through 1st-2nd and 3rd that way and it won't slip. I've tried the start from a stop in second gear and smell for something, but I don't smell anything out of the ordinary, it doesn't make any weird noises and always GOES when I do it that way.
Any ideas as to what this hesitating might be? Any other tests I can perform to see if it's the clutch or something?