Peugeot 3008 2014 1.6 turbo - engine fault at 5000rpm

1. At about 5000 rpm up a hill I get an engine fault message with codes P1336 and P1339. Car gets shaky.
2. Restarting the car and the shakiness is gone. Clearing the codes and car is back to normal, runs perfect until I hit 5000rpm again. It’s fairly consistent.
3. Changed spark plugs and coils to new ones, original spec. Same problem.
4. Local mechanic predicted a problem with injector #3. We added a cleaning solution to the fuel (3/4 tank). Was told to drive until tank is empty.

Did any of you encounter this problem? What are your recommendations?