I have finally fixed the misfire issue. Now when im driving around 45+, its almost like a hum not wanting to downshift unless i get on it. I already tried dr. tranny a couple months ago but nothing. its an annoying sound and doesnt sound healthy for the truck. any guesses.

 

I also have a humming or gear type whine at around 50 MPH and above, gets quieter above 50. What research I have done points to an issue in the rearend, with either incorrect gear tolerance, possible bad bearings, limited slip clutches possibly. Mine has done it over a year and due to that fact I have not gone into panic repair mode. While annoying I am not convinced it is going to break anytime soon. Or it would have already. Some have suggested a total rearend overhaul, but my 04 has cost me too much in the last year so I am holding off until symptoms get more severe. I had the cover off and changed oil in it over a year ago, and put in a heavier grade, which seemed to increase the volume level so I am leaning to a gear tolerance thing, which may cure itself one of these days when it wears out enough, or blows up.