I drive a xf wagon on gas its gutless of the line but good on fuel my problem is she used to sit on 150 klicks going up desent hills and maxed out at 160 on the flat now she maxses out at 140 on the flat and 90 on the hills I tryed replacing the converter it gave her 10 kays tryd tightening the exelerater it gave her her better take of s#*t laods more take of but nuthing on the hills it whont even go past 150 going down hill
checked the brakes for binding nope not that all i can think of is the trans cuold it be the trans cosidering trans dosnt slip

Maybe because it sounds like you have thrashed the living s**t out of it ... and the car can't take it anymore ... Me thinks it's dying on you.

Shouldn't be doing those speeds on the public roads anyway.

you have changed spark plugs, air filter etc?
there's no rag you use for wiping the dipstick
caught in the air intake?