Lack of power and roaring?
 

Totally new to F150's and pickups in general but hopefully you all can help me understand if this is normal or something off.

I have a Lincoln Mark LT with the 5.4 3v

On cold start the truck's RPM is around 1,200~ for about 1min (louder roar) then dips down to 600-800 (softer). When I place it in "D" and start to drive it seems like there is limited power and the truck roars again as I give it gas.

I will be replacing the tensioner and idle pullies as they squeel a little. When I try to turn the fan it has resistance but rotates fully (when cold)

This could be so many things. Can you give all the recent service history and any other problems or ways to explain it?

Plugs were changed 30,000km ago, along with fluids. Brakes are not sticking and no CEL's are present.

In addition to my initial questions, I also notice the squeeling getting louder based on rpm, im assuming that this could be an tensioner/pully related issue.

EDIT: The roaring sounds like the fan clutch, the squealing sounds like a pulley (tensioner, idler, etc.). I've had both issues before. I'd also recommend changing the belt when you change the pulley that's bad.

How does one test if the fan clutch is bad? Up here they are extremely expensive from Ford.

Also a simple check that some people have described as a light roar could be the foam at the bottom of the air box has deteriorated and the air box is sucking in extra air. Simple check and fix if it is.

You buy a new one, replace the old one, and when the truck runs better you come back and thank me for the advice.

Or you can take it to a shop and have them diagnose it and replace it for you. Then come back here and let us know that was it so I can say "I told you so".

This is true, but this would not make the truck run like it is extremely low on power, as OP states. The broken fan clutch causing the "roar" with RPM increase draws lots of power away from the drivetrain.

I agree with you "Mr. I Told You So" :jester: it is most likely the fan clutch, but sucking in too much air can also throw the fuel air mixture out of wack and result in slight loss of power. One persons extremely low on power is anothers slight loss depending on many different details. Also if my suggestion is wrong then 1) it wont hurt to fix it if the foam is rotted away and 2) my suggestion is anywhere from 10 to 100 times cheaper. Just offering some cheap possibilities too. Again I agree you're probably right in this situation though.

I've been working on cars for the last 20yrs (motor swaps, suspensions, turbo's, etc) so Im able to do the work myself. Im just a newbie when it comes to F150/Trucks so all the insight/help is appreciated.

Does anyone recommend an aftermarket fan clutch or is OEM my best bet?

I called Ford, they want $260 while Partsource (similar to Napa) wants $103 for a Hayden branded unit.