I put alot of miles on my Xterra because I work in the Rd. I've never had to do more than change the oil and the brakes. I noticed yesterday on the last leg of a 600 mile drive that it was periodically making a clicking/squeaking noise and I'm losing power and it's feeling sluggish between 25-45 mph once I hit 50 and up it goes away. Any suggestions on what could possibly be causing this? I read on google it could possibly be the air flow sensor. I just wanted to get an opinion from people that are familiar with this particular vehicle. It's a 2011 standard model.