2002 225 efi running ruff need help

[Scugog]

Hi all have a 225 efi seems to be running ruff no power compresssion is great fuel pressure bang on been on scan no codes ran on external tank no difference air sensor was out of spec but changed new plugs champions new seperator firing on all cylinders but 5 and 6 seem to be missing and wet dropd lower unit wondering if exhaust gasket at power head could cause this not sure if i could see gasket in one of ports ran motor with no lower to see if water was fouling plugs no change this is in shop for 2 weeks cant afford the labour to keep looking running out of cash any help would be great thks.