Assuming valve train is operating correctly and there is sufficient compression; engine misfires can be due to a variety of things.
1. Bad plug (this happened to me and nearly drove me mad) 2. ECU (got to ascertain the trigger signal is being sent) 3. Coil (swap-to-test or measure) 4. PTU (this one is pretty much a swap-to-test) 5. Harness (bad contact) 6. Injector (this is the combo) 7. Cylinder head gasket (this is accompanied by overheating or water in oil and others