b20 acceleration probs

i have a b20 vtec in my 89 crx si, and it will stumble below 3000rpm and when the vtec kicks in at 4800....the knock sensor isnt hooked up, but i dont think that would be my problem..also im not sure if i have the vacuum lines hooked up correctly. would this cause the stumbling problems. so i was wondering if anyone had the vacuum diagram for a b20 or if someone could help me out.
thanks

what kind of head do you have on it?