I have a 91 crx with a b16 swap and I am having problems with the vtec.No matter what rpm i set it to it seems to hesitate if anyone can help I would greatly appreciate it.  

some of the others in the community who have a ton more experience with these issues will give some better answers, however i can offer you a starting point. i have a similar setup and was experiencing the same issue, so i cleaned the filter inside the vtec solenoid (which was clogged with what appeared to be very old oil sediment) and the problem was solved. also you may want to post what obd and ecu you are running. good luck!