this is the closest i'll get to doing a swap for monatary reasons,i have the d16 intake put it on,idle bounces & i have 1 coolent port with nothing to hook it to ..
should i just put it back stock or is this an easy fix

 

You need to put a little more info in your post. What specific car and motor do you have? Did you do a MPFI conversion, or are you just swapping manifolds? You idle situation is due to a vacuum leak, most likely due to that coolant port with nothing hooked up to it. Take pics if you can and post them, it will help trouble shooting your problem.