i have a 2004 f150 4 wheel drive with 90k miles now and about 10 k miles ago my truck started making a weird raspy noise almost like a leaky exhaust gasket but ive inspected around the manifold and dont see any carbon or cant feel any exaust leaking out when im driving it feels like it is going to die until the rpms go up a little. it does this most of the time but ocasionaly it stops and runs really good does anyone have an idea what this could be or have had similar problems

 

Has the check engine light come on at all? If so, need to get the PCM scanned & find out what codes are popping up. When it feels like it's going to die, what are the rpm's? Have you had the plugs replaced on your truck yet? Could be a leaky exhaust manifold that seals after it heats up but that wouldn't make the truck run poorly.

 

i just replaced plugs my self 15 k miles ago never had the cel come on and i cant find an exhaust leak but it sounds just like that but lack off low end power the rpms run really low some times even at a consistant freeway speed it does fine when i get it to shift into passing gear