1994 Honda Civic idling trouble

Hi, i'm new here. A friend recommended me here and he say that this site is helpful.
here's the problem: I just put an turbo h22 v-tec swap in and for some reason everything run fine, but when it get to 4500 rpm the car bobble and it feel like it going to die, seem like most power is loss and the car get weak after 4500 rpm. I change the spark plug thinking it's not getting enough spark, but still same problem. My buddy say it might be the distributer but i'm not sure myself either. By the way it was already tune a few months ago, so I know it can't be that. Please help. Thanks