Air charger cooler for 8 M 32 C

I am an Engineer superintendent in one off shore copmanies, Normally we follow the PMS system mentioned in your instruction manuall regarding periodical cleaning of air charger cooler attached to MAK engine 8 M 32 C but in spite of doing this process we still have an obvious raise in exhaust temperature which is can be analyzed as a septoum for many reason, but be sure all measurments has been followed (change of fuel injector nozzles as a one set-checking of tapped clearence - maitaining of fuel injection pumps-reviewing all injection pumps index mechanism & linkages-made a complete overall for Napier turbocharger-checking of ventillation in engine room-using cooling water treatment in as per instruction manuall).....return back to air charger cooler where lately we has been instructed with change of air charger cooler which is not blocked or damged so my question, do this procedure for engine time life about 7 years is the best or the most probaply the cause of high exhaust temperatue in spite of we have a u-tube air pressure reading diffirence up to 40 cm between in & out air pressure???.......your reply is highly appreciated.