My truck for 5 years starts right up and idles fine when cold. But when i put it in drive and slowly give it gas, the engine noise is loud even on light throttle up thru probably 3rd gear? I mean it's loud. If I put it in neutral and rev it, it is the same loud engine. Not knocking, or exhaust loud but it sounds like it's over-revving. Once hot, it is quiet at start up and while revving it in neutral. Lately however it is doing this even when warmed up. Does not do this at highway speeds. Also I noticed that it will not kick down 2 gears anymore when I stomp it going about 50, it will only down shift once.
I recently replaced the water pump, radiator and thermostat.
Could any of that be an indicator?
Very confusing.
Any help appreciated.

 

in other threads i've searched they refer to this as 'roaring' which makes sense. I changed the fan clutch when I did the radiator. I'm guessing that's why it roars more now than before.

 

Yep. What you are hearing is the fan moving large amounts of air.