We call it the infamous JDM "hesitation" problem.
hesitation
In my case, the problem was the knock sensor. After I got a ecu that didn't detect the knock sensor, it stopped and ran goooooooOooood. While I had the hesitation problem, my car was seriously slow
So check it out and try to get it fixed as soon as you can, you are losing alot of power and missing out on some fun.