where do the vacuum leaks happen for spark plug #4

yes mis fire keeps comming back when u start engine next day ...don't know how to check coil i can change wire from one plug to another?i noticed idle sped-up and goes back down on start-up i tried that also ruff idle till warms-up power is good can take-off no misses..started engine for 30 sec turned off and checked plug 4 wasn't wet maybe vacuum leak but not sure where on intake?somewhere near intake for plugg 4 i guess?? what u think ty