Atmospheric pressure sensor

Hey every1. Im a trucker from ZA. I drive a 06 Freightliner Argosy 7CZ 600hp C16. Its done 1.8 mil km without any major breakdowns. Lately it lacks power and feuleco also went down from 2.18km/l to under 1.9km/l. Boost dropped by 45 kPa with no leaks found on the usual suspects. I removed the atmospheric sensor to check the oring for possible pressure leak and found it to be full of oil. Logic tells me that there shouldnt be oil. Could someone point me in the direction of a possible cause and way to solve this issue. Engine runs rough at times under load and somtimes even without load. Almost sounds if the jakes comes on while i accellerate. I hope all you Cat experts can help out this novice cat loving trucker.

Thanks in advance.

 

Thanks. Will check the turbo on monday for play and cracks.

 

Injectors were changed 4 months back and the turbo might have done bout 150 000km. Ive read that the atmos...sensor can cause the ecm to derate.

 

I will check the airtubes on monday when servicing the truck. Will give you the results on monday.

 

Atmos sensor is directly next to the oil pressure sensor on the lefthandside, just infront of the secondary fuel filter
My issue is that its filled with oil and im not sure if it should be.