Use a scan to to monitor CURRENT misfires. If a cylinder is misfiring work on that cylinder. Check connector at injector, wiring harness(shorts or opens). Remove connector on misfiring cylinder. Backprobe the connector to check for voltage with key in KOEO position. Is voltage present? Replace connector and start engine. Backprobe the connector with engine running. Is terminal pulsing? Ck injector resistance value:11.4 ohms. Ck grounds to injectors(clean and tight connection). Check connector at PCM(ECM). Replace injector. This is on overview of the troubleshooting procedure for this DTC, but you get the idea.