Spn 1326 fmi 11 and spn1322 fmi 11

[Gill Oruga]

What color charge air hose do you have on the CAC cold side? Is it blue or black?
The old black ones used to collapse at partial throttle and create misfire conditions. If it looks like a solid blue silicone one you should be okay.

Are you 100% positive the exhaust gas tube is free of soot buildup?

That hole on the exhaust manifold is awful tiny on those ISL9's. Maybe try and remove the sensor and blow air inside the tube with a rubber tip air gun to confirm.

1326/11 is a code for cylinder #4 misfire (Cummins code 5898)
1322/11 is a code for random misfire (Cummins code 5914)

Can you try swapping injector #4 with #5? Make sure to also move the fuel connectors with them.

See if the issue follows and go from there. Hope you don't have an engine brake as those can be a pain to re-adjust on the ISL9's.