When I'm on the highways doing 80mph or more my truck feels like i'm driving a Bentley. It's nice, smooth, and solid.. But I find at normal speeds it feels sluggish, noisey and keeps me guessing what is wrong.

I am not sure what if anything is wrong. It is killing me, I am going to change out the plugs when I get a chance, but I am not sure why it feels so smooth at high speed and feels like crap at slow speeds.

Any ideas?

 

Post a video of the noise.