Misfire

There are two kinds of misfires: Ignition and fuel.

For ignition:
Check plugs/wires/coils

For fuel:
Check fuel pressure regulator for a leak (Pull vacuum hose and check for presence of fuel. If there's any, replace it)
Check for all injectors firing with an automotive stethoscope. You should hear a clicking sound. If one/more are not firing, first check that there's a signal telling it to fire. If yes, replace injector. If not, check wiring harness/connector, and/or computer.
Check injector flow pattern and for a clogged/leaking injector.