If your coil is running hot its ok, very hot?,,,,,,,,, not ok. If you have a new coil, please also check if its the type that uses a ballast resistor for voltage control. Rough running on the other hand could come from a number of places............leaky spark plug cables, leaky spark plugs, clogged injector nozzles, Dirty Throttle flap, air leak on the inlet manifold and some other points. Spending money on a new coil will definitely not solve your rough idle.