New 4g eclipse owner -help needed

hi guys thanks for having me in the forum so I recently purchased a 2007 eclipse gt and I don’t know if this is something I should be worried about I can’t tell if it’s clutch slipping or just how the car delivers power put when I step on it my eclipse revs out really high with some power gain then rpm’s drop back to where they were and then begins to rev out again with all my power again the mods done to the car are a cold air intake and a custom catback exhaust. Thanks in advance.