i have an 89 civic si with a b16a swap. my problem is that right before i go into vtec it boggs. it only does it right when it hits vtec. after vtec is engaged its fine. just started acting like this. any ideas. i recently put on ctr cams, skunk 2 manifold, vafc. i thought it would go away by getting the vafc but it didnt.

 

you should be able to tune the vafc to smoothe it out. i dont have one so i dont know how, i just know you can.