cruising down the freeway at 70 mph, give or take, and out of nowhere a sound like a helicopter came up. it got louder and faster as the motor was revved up. im thinking it could be a bent intake valve because when i popped the hood i could feel air coming out of the filter while it was idling. whenever the sound would come, a puff of air would come from the turbo out the filter. the EGTs were higher than normal at 70 and the boost was a little bit lower. questions are what could the problem most likely be and what can i do to rectify the situation? somewhat cheaply? thanks