I HAVE A MISFIRE IN CYLINDER 6.I CHANGED THE PLUGS AND THE INJECTOR.

I HAD THE COIL YESTED AND IT WAS GOOD . A FRIEND SAYS IT MITE BE IN THE HEADS . DO YOU THINK THATS TRUE

Doubt the heads are the issue. Get some carb cleaner and spray the vacuum intake lines and see if there is a vacuum leak somewhere, while running. The engine will surge if there is one. Also, swap coils and see if the misfire moves to the location where you put cylinder #6 coil.