Misfire on cylinders 1,2,3, and 4 on a 302HO V8 1992 Mustang?
I'm assuming it's fuel injection engine. When you did compression test did you shut off fuel pump and check all 8 cyls. with throttle open and cranked same amount of turns? If not you wont get correct reading. Have you done an obd scan to check for trouble codes? Spark plugs black and wet can be injector problem delivering too much fuel which are computer controlled, so before digging into engine suggest an OBD scan for codes and to read sensor parameters first. Usually compression should be around 150psi all cylinders.