Unknown problem and sounds

[brigantef]

I have a 02 f250 with 213000 miles. when im driving there is a rushing air sound when it shifts. over the past couple months i have noticed that the air rushing sound starts to get louder as the rpm increase in the higher gears(around 45 mph and 55 mph) as well as i am loosing fuel mileage (17 down to 14). a couple weeks ago it threw a code for exhaust pressure control valve fault (P0475) so i disconnected the ebp valve sensor at the front of the engine. the sounds and symptoms started before the ebp valve so i think its the wastegate. any thoughts as to what is the problem.