Jeff has a great idea.
Sometimes we find the wire inside the sheathing breaks close to the crimp of the Connector.
When it is misfiring use a pair of needle nose pliers, while holding 1 wire close to the connector wiggle the other wire, push , pull .
Than the same with the other wire.
Sometimes the female, push on connector gets spread and loose enough to cause poor connection.
If it's not at the connector work your way away from the injector, twisting the wire as you go.
You can go to a parts st
ore, NAPA, and Harbor Freight and buy noid light kit to plug into the harness to confirm a signal/ blink.
Next is ohm test harness, injector to ecm.