Just got some questions.. got code P1661, is that misfire related?

Also it was takin in and is the engine is missing under load on cylinder 4&5. Plugs, wires, and coil have all be replaced... time for optispark to fail? Looks like im lookin for one of these junkers now. Thanks guys

 

1661 is the SES light circuit. See if the light comes on when the ignition is first turned on. If it does, you have a wiring issue more than likely.