I'll preface this by saying two things: 1) That today was the first REAL cold day we've had this year (20*F), and 2) I've been having problems with the throttle response cutting out (orange wrench light comes on), and the truck's been stalling out...a couple guys pointed me towards throttle body electronics, and said if it persists the throttle body may need to be replaced. It's happened probably 4-6x in the past couple months.

Not sure if any of that may be relevant, but with that said, I got in my truck this morning, and as soon as I pulled out my driveway, it started making a "rubbing" noise that got louder and higher-pitched the faster I went...by 30mph it was loud. The best way to describe it is similar to the sound of the tire rubbing against the plastic wheel well liner. Turned around and limped back to my house. By the time I got there, the engine had warmed up a bit and the noise wasn't as obvious. I took it out onto the street again and the noise was largely gone...I tried limping the ~5 miles to work, and by the time I got there, the rubbing was gone. Now, I could hear a "whoosh" sound, like air in a line. Throttle response also seemed a little delayed, and it may be in my head, but I've been noticing potential delay for the past 2 weeks or so...have to step on it a bit more. I figured this was the same problem with the throttle position sensor not communicating properly with the ECU. But I have no idea.

Thanks in advance for the help...I'm driving (hopefully) about 20 mins. to another job in the morning, and 20 mins. back to this one on Sunday morning. Hoping it's an easy fix... :o

 

Oh, and it sounds like it's coming from the passenger's side of the truck. It's definitely forward of the cab.

And yes, I checked to see if anything was actually rubbing. Heh. Could it be that the fluid (tranny?) is just too viscous in the cold = friction? I've had this truck new since April 06 and had no problems with it in New England weather before.

EDIT x2: It makes the noise regardless of whether throttle or brake is applied or not. Also, when it happened, as I slowed down, I shifted into neutral and the noise continued.

It's an 06 XLT 5.4L Crew cab BTW.

Thanks for any help!