hey honda tech, i just installed a d16z6 head (rebuilt and machined) to my d16y7 block (vitara pistons, stock bore, block guard) and once is started it up it was idling at 3000 rpm, then i started it up again it fluctuates idle between 1000 rpm and 2500 rpm. i did found a vacuum leak coming from where the intake manifold meets the head and since i was using an oem d16y8 intake manifold gasket i figured that was the problem so i purchase a d16az6 intake manifold gasket and installed it and it is still doing the same thing. i have an edelbrock performer x intake manifold but it was from my y8, would that make any difference? thanks in advance

 

Try replacing or cleaning the iacv